Re: I fixed a broken spoke!

Quoted message said:

The most likely explanation for an occasional spoke breaking is
variation in the spoke material. The bending and tensioning and so
forth are quite regular. If pinching the spokes were solving some
residual stress problem, the same problem would be causing all the
other spokes to fail.

No idea if this is relevant or not, but if the spokes in question are
some of those made from the Korean steel which has now been
acknowledged to have been below spec on strength and flaws, then the
breakage is most likely due to that.

Quoted message said:

There's no question that improvements in spoke material have reduced
spoke failure dramatically. Spokes are still being bent and formed the
same way, but ten years after his book's first edition, Jobst
high-lighted the improvement in spokes in his 3rd edition:

"It appears that the better spokes now available would have made the
discovery of many of the concepts of this book more difficult for lack
of failure data. I am grateful in retrospect for the poor durability of
earlier spokes. They operated so near their limits that durability was
significantly altered by the techniques that I have outlined."

--Jobst Brandt, "The Bicycle Wheel," 3rd Edition, 1993, p.124

And the speed with which spoke failures became common again when just
one prolific mill was producing substandard wire, was quite
demonstrative of the accuracy of Jobst's statements.

Quoted message said:

So pinch 'em and expect improved seating, but don't expect miracles in
residual stress relief. That's achieved just by raising the tension to
normal levels.

OTOH, it couldn't hurt, either, and once in a while it'll be just
enough to reveal the one ready-to-fail spoke lurking in the bunch.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Quoted message said:

dgk said:

Quoted message said:

Joseph Santaniello writes:

> If you are breaking non-drive side spokes, this indicates without a
> doubt that they are [censored] spokes. (based on info from your previous
> posts, that you don't weigh 400lbs,etc)

Even the best spokes fail if they are not formed to the hub and stress
relieved. Don't push it off on the spoke manufacturer when it's the
builder who needs to take measures to make the wheel durable.

Jobst Brandt

Stress relief is just going around the wheel sort of pinching the
spokes?

Dear DGK,

Forgive me, but your innocent response is too good not to cross-post to
rec.bicycles.tech.

THANKS! I can't recall the last time someone called anything about me
"innocent". It's almost like being carded.

Carl Fogel said:

Quoted message said:

Quoted message said:

> If you are breaking non-drive side spokes, this indicates without
> a doubt that they are [censored] spokes. (based on info from your
> previous posts, that you don't weigh 400lbs,etc)

Quoted message said:

Quoted message said:

Quoted message said:

Even the best spokes fail if they are not formed to the hub and
stress relieved. Don't push it off on the spoke manufacturer when
it's the builder who needs to take measures to make the wheel
durable.

Quoted message said:

Quoted message said:

Stress relief is just going around the wheel sort of pinching the
spokes?

Quoted message said:

Forgive me, but your innocent response is too good not to cross-post
to rec.bicycles.tech.

Don't be so condescending about finding an opening to present your
belief in the misplaced experiments you performed to support your
belief in stress relief. You are not forgiven.

Quoted message said:

While pinching spoke pairs together probably helps to seat the
spokes in the hub and the nipples in the rim, tests showed no
further residual stresses being relieved after ordinary spoke
tension, even when tension was much higher than the typical 60-lb
tension increase that other testing shows can be achieved by
pinching.

Consider that typically an outbound spoke is bent to yield when
tightened after a wheel is laced. This is apparent from its elbow
bend that was obtuse when new and acute after a wheel build. That the
elbow that is raised to tensile yield during tensioning should be
evident because all additional tension can only yield that portion of
the spoke in the elbow further. It will remain at yield, there being
no mechanism to make it less than that.

Because no over-tensioning followed by relaxation (manually stretching
spokes) is used, the elbow must be at yield in the finished wheel.
Therefore, the residual stress from elbow modification remains with
that spoke that is tensioned to less than yield stress in the absence
of stress relieving.

Your heating experiment was done on a relaxed spoke and does not
reveal what the tension was on the outside of an elbow bend, for
instance. If you raised your spoke tension to yield stress prior to
relaxing it and heating, then it is evidence of stress relieving by
momentary over-stress, nothing more.

Quoted message said:

I pinched spokes together on various wheels with known forces and
measured the tension changes. Despite the impressive bending, the
spoke tension rose only about 55~65 for a 60 lb pinch. (The bending
was not due to the spokes being stretched by tremendous tension
increases, but to the slack gained when the rims bent into faint N
or Z shapes.)

Any momentary overload will cause yielding in the portions of a spoke
that are at tensile yield stress and relaxing that overload
constitutes stress relief. I don't see what is not obvious about that
process.

Jobst Brandt

Quoted message said:

Carl Fogel said:

Quoted message said:

>> If you are breaking non-drive side spokes, this indicates without
>> a doubt that they are [censored] spokes. (based on info from your
>> previous posts, that you don't weigh 400lbs,etc)

Quoted message said:

Quoted message said:

> Even the best spokes fail if they are not formed to the hub and
> stress relieved. Don't push it off on the spoke manufacturer when
> it's the builder who needs to take measures to make the wheel
> durable.

Quoted message said:

Quoted message said:

Stress relief is just going around the wheel sort of pinching the
spokes?

Quoted message said:

Forgive me, but your innocent response is too good not to cross-post
to rec.bicycles.tech.

Don't be so condescending about finding an opening to present your
belief in the misplaced experiments you performed to support your
belief in stress relief. You are not forgiven.

[snip]

Dear Jobst,

Don't be such a pompous, paranoid ass, particularly 11 days after the
post first appeared.

Cheers,

Carl Fogel

Quoted message said:

Carl Fogel said:

Quoted message said:

>> If you are breaking non-drive side spokes, this indicates without
>> a doubt that they are [censored] spokes. (based on info from your
>> previous posts, that you don't weigh 400lbs,etc)

Quoted message said:

Quoted message said:

> Even the best spokes fail if they are not formed to the hub and
> stress relieved. Don't push it off on the spoke manufacturer when
> it's the builder who needs to take measures to make the wheel
> durable.

Quoted message said:

Quoted message said:

Stress relief is just going around the wheel sort of pinching the
spokes?

Quoted message said:

Forgive me, but your innocent response is too good not to cross-post
to rec.bicycles.tech.

Don't be so condescending about finding an opening to present your
belief in the misplaced experiments you performed to support your
belief in stress relief. You are not forgiven.

Quoted message said:

While pinching spoke pairs together probably helps to seat the
spokes in the hub and the nipples in the rim, tests showed no
further residual stresses being relieved after ordinary spoke
tension, even when tension was much higher than the typical 60-lb
tension increase that other testing shows can be achieved by
pinching.

Consider that typically an outbound spoke is bent to yield when
tightened after a wheel is laced. This is apparent from its elbow
bend that was obtuse when new and acute after a wheel build. That the
elbow that is raised to tensile yield during tensioning should be
evident because all additional tension can only yield that portion of
the spoke in the elbow further. It will remain at yield, there being
no mechanism to make it less than that.

Because no over-tensioning followed by relaxation (manually stretching
spokes) is used, the elbow must be at yield in the finished wheel.
Therefore, the residual stress from elbow modification remains with
that spoke that is tensioned to less than yield stress in the absence
of stress relieving.

Your heating experiment was done on a relaxed spoke and does not
reveal what the tension was on the outside of an elbow bend, for
instance. If you raised your spoke tension to yield stress prior to
relaxing it and heating, then it is evidence of stress relieving by
momentary over-stress, nothing more.

Quoted message said:

I pinched spokes together on various wheels with known forces and
measured the tension changes. Despite the impressive bending, the
spoke tension rose only about 55~65 for a 60 lb pinch. (The bending
was not due to the spokes being stretched by tremendous tension
increases, but to the slack gained when the rims bent into faint N
or Z shapes.)

Any momentary overload will cause yielding in the portions of a spoke
that are at tensile yield stress and relaxing that overload
constitutes stress relief. I don't see what is not obvious about that
process.

i'm an [ex] metallurgist, and i see nothing "obvious" about this
supposition at all. you repeatedly prove know nothing about materials
[particularly fatigue or deformation - metal yields to zero "brick
dragging" b.s!!!!], you've done no testing, you have no data. you even
have the temerity to claim "invention" of wheel building practice that
dates before your birth. and yet here you are, years after being
confronted with facts and data that would allow you to correct your
mistakes, still in denial. you've even been asked to perform simple
[cheap] industry standard testing that could /prove/ you correct if
you're so damned confident, but you won't. why not?

this is not a technology problem: this is an i.q. problem.

On 2006-12-31, [email hidden] <[email hidden]> wrote:
[snip]

Quoted message said:

Your heating experiment was done on a relaxed spoke and does not
reveal what the tension was on the outside of an elbow bend, for
instance. If you raised your spoke tension to yield stress prior to
relaxing it and heating, then it is evidence of stress relieving by
momentary over-stress, nothing more.

The experiment was intended as evidence of that. But what it indicated
is that the normal tensioning of a spoke as a wheel is built is enough
to relieve any residual stresses that might be present in the elbow,
either from manufacture or introduced during the build when correcting
the spoke line.

We have heard:

1. Not uncontentious theories explaining why there should be residual
stress.
2. Experiments indicating the contrary.
3. Reasonable anecdotal evidence that various processes (squeezing, the
Mavic method, the Trek method) whose supposed effects include
stress-relief reduce spoke failures.
4. Plenty of other reasons besides presence of residual stress why
spokes might fail.

We have not heard:

1. Any evidence that residual stress exists in a newly formed spoke
2. or in a spoke just built into a wheel, elbow-corrected and tensioned.
3. Any evidence that residual stress ever contributed to the failure of
a spoke.

I don't see how we are expected to draw any other conclusion from this
than that as far as we can tell residual stress is unlikely to be
related to spoke failure.

Ben C? said:

[snip]

Quoted message said:

Quoted message said:

Your heating experiment was done on a relaxed spoke and does not
reveal what the tension was on the outside of an elbow bend, for
instance. If you raised your spoke tension to yield stress prior
to relaxing it and heating, then it is evidence of stress relieving
by momentary over-stress, nothing more.

Quoted message said:

The experiment was intended as evidence of that. But what it
indicated is that the normal tensioning of a spoke as a wheel is
built is enough to relieve any residual stresses that might be
present in the elbow, either from manufacture or introduced during
the build when correcting the spoke line.

Hold it! Let's review a few points. Do you not believe that:

1. A spoke that has been plastically deformed at the elbow has reached
yield stress?

2. That this stress is tensile.

3. That tensioning a spoke does not raise stress in its parts that
have no residual stress to more than half its yield.

4. That adding tension to the spoke guarantees that the stress at the
outside of the elbow remains at yield, that being the highest load
it can withstand.

5. Therefore, adding tension to a spoke cannot relieve that condition
unless an overload is applied and relaxed.

6. That cyclic loading (as a spoke experiences) at yield stress causes
fatigue failures in spokes.

Quoted message said:

We have heard:

Quoted message said:

1. Not uncontentious theories explaining why there should be
residual stress.

I have just reviewed that above.

Quoted message said:

2. Experiments indicating the contrary.

The experiment does not demonstrate that and there lies the
contention.

Quoted message said:

3. Reasonable anecdotal evidence that various processes (squeezing,
the Mavic method, the Trek method) whose supposed effects include
stress-relief reduce spoke failures.

Yes?

Quoted message said:

4. Plenty of other reasons besides presence of residual stress why
spokes might fail.

Most of which are spurious and given in an effort to prove that there
is no residual stress.

Quoted message said:

We have not heard:

Quoted message said:

1. Any evidence that residual stress exists in a newly formed spoke

Not at all. When a piece of steel is cold formed, as spokes are,
there is always residuals stress. That is why such parts, if
subjected to high loads are thermally stress relieved. The reason
there is residual stress has been explained often in this forum.

Briefly, when a spoke is bent far enough to retain a new shape, it has
been plastically deformed. That its outer parts exceeded yield stress
and that the inner part, acting as a thinner member does not reach
yield, is shown diagrammatically in engineering texts. That his is
the case can be demonstrated with varying thicknesses of wire and how
far they must be bent to take on a curved shape. Therefore, when the
spoke is relaxed it springs back to a lesser bend but does not become
straighten again.

The inner part of the spoke, not having reached yield wants to return
to its straight position while the outer part does not. This
difference constitutes residual stress, with tension on the inside of
the bend and compression on the outside.

That this condition is reversed if the bend is forcefully held at
maximum curvature should be evident. The surface of the bent spoke is
then in tension on the outside and in compression on the inside of the
bend, from the applied force.

Quoted message said:

2. or in a spoke just built into a wheel, elbow-corrected and
tensioned.

Elbow correction is part of stress relieving intended to prevent
cyclic flexing in service but it does not remove the residual stress
caused by that bend operation.

Quoted message said:

3. Any evidence that residual stress ever contributed to the failure
of a spoke.

How else do you explain that a spoke that is tensioned to less than
half its yield stress fails at the elbow in a relatively short time?
It fails because there are high stress points at that place and that
spokes that don't break must have lower stress. The lower stress is
achieved by stress relief and that this is possible by mechanical
means has also been explained in great detail.

Quoted message said:

I don't see how we are expected to draw any other conclusion from
this than that as far as we can tell residual stress is unlikely to
be related to spoke failure.

That is what I find so inexplicable in this discussion. On the one
hand, detailed explanations seem to be too cryptic to understand while
a small number of contributors put up explanations why these spoke
failures are not stress related.

Jobst Brandt

Quoted message said:

Ben C? said:

[snip]

Quoted message said:

Quoted message said:

Your heating experiment was done on a relaxed spoke and does not
reveal what the tension was on the outside of an elbow bend, for
instance. If you raised your spoke tension to yield stress prior
to relaxing it and heating, then it is evidence of stress relieving
by momentary over-stress, nothing more.

Quoted message said:

The experiment was intended as evidence of that. But what it
indicated is that the normal tensioning of a spoke as a wheel is
built is enough to relieve any residual stresses that might be
present in the elbow, either from manufacture or introduced during
the build when correcting the spoke line.

Hold it! Let's review a few points. Do you not believe that:

1. A spoke that has been plastically deformed at the elbow has reached
yield stress?

I believe that.

Quoted message said:

2. That this stress is tensile.

Yes, in my understanding when you bend it at the elbow, you are putting
the outside of the bend in tension and compressing the inside.

Quoted message said:

3. That tensioning a spoke does not raise stress in its parts that
have no residual stress to more than half its yield.

Yes-- I don't think normal tensioning is enough to yield the spoke, even
at the elbow.

Quoted message said:

4. That adding tension to the spoke guarantees that the stress at the
outside of the elbow remains at yield, that being the highest load
it can withstand.

I don't understand this.

I would have thought all of the spoke would be at less than yield
throughout the entire build process except for the moment at which you
plastically deform it at the elbow, after which it springs back a bit,
not remaining at yield while you carry on truing and tensioning etc.

Quoted message said:

5. Therefore, adding tension to a spoke cannot relieve that condition
unless an overload is applied and relaxed.

I think I follow this, given 4, but 4 is the sticking point.

Quoted message said:

6. That cyclic loading (as a spoke experiences) at yield stress causes
fatigue failures in spokes.

I believe that cyclic loading causes fatigue failures, but don't see why
it has to be at yield stress.

I realize that generally the higher the mean stress in a stress cycle,
the shorter the number of cycles to failure, so being at yield stress
would certainly exacerbate the problem. But I don't see how any part of
the spokes can be at yield stress in the built wheel. Yield stress is
very high for a steel spoke.

Quoted message said:

Quoted message said:

We have heard:

Quoted message said:

1. Not uncontentious theories explaining why there should be
residual stress.

I have just reviewed that above.

Yes, I appreciate that.

Quoted message said:

Quoted message said:

2. Experiments indicating the contrary.

The experiment does not demonstrate that and there lies the
contention.

I agree there's also some contention there, I remember two points:

1. Why did the carbon steel spoke bend the wrong way.
2. Does the test need to be performed on a spoke that remains tensioned,
instead of after it's been relaxed?

I'm not clear on the reasons for 2, and in spite of 1, I still find the
fact that the spokes clearly unbent on heating unless they were
stress-relieved by modest tensioning quite convincing.

Quoted message said:

Quoted message said:

3. Reasonable anecdotal evidence that various processes (squeezing,
the Mavic method, the Trek method) whose supposed effects include
stress-relief reduce spoke failures.

Yes?

Yes!

Quoted message said:

Quoted message said:

4. Plenty of other reasons besides presence of residual stress why
spokes might fail.

Most of which are spurious and given in an effort to prove that there
is no residual stress.

Is it spurious to suggest that fatigue might nucleate around surface
cracks and "orange peel" left after forming in poor quality spokes?

Is it spurious to believe that spokes that are too loose to the point
that load exceeds pretension in use will suffer premature fatigue
failure because of flexing?

[neither are rhetorical questions].

Quoted message said:

Quoted message said:

We have not heard:

Quoted message said:

1. Any evidence that residual stress exists in a newly formed spoke

Not at all. When a piece of steel is cold formed, as spokes are,
there is always residuals stress. That is why such parts, if
subjected to high loads are thermally stress relieved. The reason
there is residual stress has been explained often in this forum.

Fair enough, it has been explained that if you bend a bit of wire it
contains residual stresses, and I can follow that, so unless it's
relieved somehow, some residual stress ought to be present after
forming.

[snip]

Quoted message said:

That this condition is reversed if the bend is forcefully held at
maximum curvature should be evident. The surface of the bent spoke is
then in tension on the outside and in compression on the inside of the
bend, from the applied force.

Today I bent two lengths of spoke, one of which is kept in tension by
the ends being forced into a keyring, and put both in a jar of saturated
salt water. If anything interesting happens, then I'll put a new spoke
in there too and see if it's possible to detect residual stress at the
elbow using this method.

You may be convinced it's there anyway, but it will help some of the
rest of us.

Quoted message said:

Quoted message said:

2. or in a spoke just built into a wheel, elbow-corrected and
tensioned.

Elbow correction is part of stress relieving intended to prevent
cyclic flexing in service but it does not remove the residual stress
caused by that bend operation.

Unless normal spoke tensioning serves to relieve the residual stress.

Quoted message said:

Quoted message said:

3. Any evidence that residual stress ever contributed to the failure
of a spoke.

How else do you explain that a spoke that is tensioned to less than
half its yield stress fails at the elbow in a relatively short time?

My two top explanations are (a) flexing at the elbow because the spoke's
too loose and the load exceeds its pretension in normal use and (b)
surface imperfections in the elbow in poor quality spokes.

Quoted message said:

It fails because there are high stress points at that place and that
spokes that don't break must have lower stress. The lower stress is
achieved by stress relief and that this is possible by mechanical
means has also been explained in great detail.

I do believe it's possible. But so are alien abductions, and I don't
think they happen.

Quoted message said:

Quoted message said:

I don't see how we are expected to draw any other conclusion from
this than that as far as we can tell residual stress is unlikely to
be related to spoke failure.

That is what I find so inexplicable in this discussion. On the one
hand, detailed explanations seem to be too cryptic to understand

Certainly I don't understand some of your explanations, mainly point 4
above:

Quoted message said:

4. That adding tension to the spoke guarantees that the stress at the
outside of the elbow remains at yield, that being the highest load
it can withstand.

and what's wrong with the other explanations for spoke failure.

Ben C said:

Quoted message said:

Ben C? said:

[snip]
> Your heating experiment was done on a relaxed spoke and does not
> reveal what the tension was on the outside of an elbow bend, for
> instance. If you raised your spoke tension to yield stress prior
> to relaxing it and heating, then it is evidence of stress relieving
> by momentary over-stress, nothing more.
The experiment was intended as evidence of that. But what it
indicated is that the normal tensioning of a spoke as a wheel is
built is enough to relieve any residual stresses that might be
present in the elbow, either from manufacture or introduced during
the build when correcting the spoke line.

Hold it! Let's review a few points. Do you not believe that:

1. A spoke that has been plastically deformed at the elbow has reached
yield stress?

I believe that.

Quoted message said:

2. That this stress is tensile.

Yes, in my understanding when you bend it at the elbow, you are putting
the outside of the bend in tension and compressing the inside.

Quoted message said:

3. That tensioning a spoke does not raise stress in its parts that
have no residual stress to more than half its yield.

Yes-- I don't think normal tensioning is enough to yield the spoke, even
at the elbow.

Quoted message said:

4. That adding tension to the spoke guarantees that the stress at the
outside of the elbow remains at yield, that being the highest load
it can withstand.

I don't understand this.

I would have thought all of the spoke would be at less than yield
throughout the entire build process except for the moment at which you
plastically deform it at the elbow, after which it springs back a bit,
not remaining at yield while you carry on truing and tensioning etc.

Quoted message said:

5. Therefore, adding tension to a spoke cannot relieve that condition
unless an overload is applied and relaxed.

I think I follow this, given 4, but 4 is the sticking point.

Quoted message said:

6. That cyclic loading (as a spoke experiences) at yield stress causes
fatigue failures in spokes.

I believe that cyclic loading causes fatigue failures, but don't see why
it has to be at yield stress.

I realize that generally the higher the mean stress in a stress cycle,
the shorter the number of cycles to failure, so being at yield stress
would certainly exacerbate the problem.

indeed - i was unclear about that in my response. when a material is
stress cycled at yield, fatigue life is very short, just a few cycles.
clearly that's not what we see with a bicycle spoke.

fact is, fatigue initiates and propagates at stress /well/ below yield,
which is how the term "fatigue" was coined since the material is /well
below/ yielding. for materials that don't evidence strain aging,
fatigue can be shown to initiate at stress as low as about 30% of yield.

Quoted message said:

But I don't see how any part of
the spokes can be at yield stress in the built wheel. Yield stress is
very high for a steel spoke.

Quoted message said:

Quoted message said:

We have heard:
1. Not uncontentious theories explaining why there should be
residual stress.

I have just reviewed that above.

Yes, I appreciate that.

Quoted message said:

Quoted message said:

2. Experiments indicating the contrary.

The experiment does not demonstrate that and there lies the
contention.

I agree there's also some contention there, I remember two points:

1. Why did the carbon steel spoke bend the wrong way.
2. Does the test need to be performed on a spoke that remains tensioned,
instead of after it's been relaxed?

I'm not clear on the reasons for 2, and in spite of 1, I still find the
fact that the spokes clearly unbent on heating unless they were
stress-relieved by modest tensioning quite convincing.

Quoted message said:

Quoted message said:

3. Reasonable anecdotal evidence that various processes (squeezing,
the Mavic method, the Trek method) whose supposed effects include
stress-relief reduce spoke failures.

Yes?

Yes!

Quoted message said:

Quoted message said:

4. Plenty of other reasons besides presence of residual stress why
spokes might fail.

Most of which are spurious and given in an effort to prove that there
is no residual stress.

Is it spurious to suggest that fatigue might nucleate around surface
cracks and "orange peel" left after forming in poor quality spokes?

Is it spurious to believe that spokes that are too loose to the point
that load exceeds pretension in use will suffer premature fatigue
failure because of flexing?

[neither are rhetorical questions].

Quoted message said:

Quoted message said:

We have not heard:
1. Any evidence that residual stress exists in a newly formed spoke

Not at all. When a piece of steel is cold formed, as spokes are,
there is always residuals stress. That is why such parts, if
subjected to high loads are thermally stress relieved. The reason
there is residual stress has been explained often in this forum.

Fair enough, it has been explained that if you bend a bit of wire it
contains residual stresses, and I can follow that, so unless it's
relieved somehow, some residual stress ought to be present after
forming.

[snip]

Quoted message said:

That this condition is reversed if the bend is forcefully held at
maximum curvature should be evident. The surface of the bent spoke is
then in tension on the outside and in compression on the inside of the
bend, from the applied force.

Today I bent two lengths of spoke, one of which is kept in tension by
the ends being forced into a keyring, and put both in a jar of saturated
salt water. If anything interesting happens, then I'll put a new spoke
in there too and see if it's possible to detect residual stress at the
elbow using this method.

You may be convinced it's there anyway, but it will help some of the
rest of us.

Quoted message said:

Quoted message said:

2. or in a spoke just built into a wheel, elbow-corrected and
tensioned.

Elbow correction is part of stress relieving intended to prevent
cyclic flexing in service but it does not remove the residual stress
caused by that bend operation.

Unless normal spoke tensioning serves to relieve the residual stress.

Quoted message said:

Quoted message said:

3. Any evidence that residual stress ever contributed to the failure
of a spoke.

How else do you explain that a spoke that is tensioned to less than
half its yield stress fails at the elbow in a relatively short time?

My two top explanations are (a) flexing at the elbow because the spoke's
too loose and the load exceeds its pretension in normal use and (b)
surface imperfections in the elbow in poor quality spokes.

Quoted message said:

It fails because there are high stress points at that place and that
spokes that don't break must have lower stress. The lower stress is
achieved by stress relief and that this is possible by mechanical
means has also been explained in great detail.

I do believe it's possible. But so are alien abductions, and I don't
think they happen.

Quoted message said:

Quoted message said:

I don't see how we are expected to draw any other conclusion from
this than that as far as we can tell residual stress is unlikely to
be related to spoke failure.

That is what I find so inexplicable in this discussion. On the one
hand, detailed explanations seem to be too cryptic to understand

Certainly I don't understand some of your explanations, mainly point 4
above:

Quoted message said:

4. That adding tension to the spoke guarantees that the stress at the
outside of the elbow remains at yield, that being the highest load
it can withstand.

and what's wrong with the other explanations for spoke failure.

Ben C? said:

Quoted message said:

Quoted message said:

[snip]

Quoted message said:

Quoted message said:

Quoted message said:

> Your heating experiment was done on a relaxed spoke and does not
> reveal what the tension was on the outside of an elbow bend, for
> instance. If you raised your spoke tension to yield stress prior
> to relaxing it and heating, then it is evidence of stress
> relieving by momentary over-stress, nothing more.

Quoted message said:

Quoted message said:

Quoted message said:

The experiment was intended as evidence of that. But what it
indicated is that the normal tensioning of a spoke as a wheel is
built is enough to relieve any residual stresses that might be
present in the elbow, either from manufacture or introduced during
the build when correcting the spoke line.

Quoted message said:

Quoted message said:

Hold it! Let's review a few points. Do you not believe that:

Quoted message said:

Quoted message said:

1. A spoke that has been plastically deformed at the elbow has
reached yield stress?

Quoted message said:

I believe that.

Quoted message said:

Quoted message said:

2. That this stress is tensile.

Quoted message said:

Yes, in my understanding when you bend it at the elbow, you are
putting the outside of the bend in tension and compressing the
inside.

Quoted message said:

Quoted message said:

3. That tensioning a spoke does not raise stress in its parts that
have no residual stress to more than half its yield.

Quoted message said:

Yes-- I don't think normal tensioning is enough to yield the spoke,
even at the elbow.

Quoted message said:

Quoted message said:

4. That adding tension to the spoke guarantees that the stress at
the outside of the elbow remains at yield, that being the
highest load it can withstand.

Quoted message said:

I don't understand this.

OK, the outside of the elbow is at yield. Additional tension makes it
stretch while it remains at yield (by definition of yield) the stress
at which the steel stretches. Therefore tensioning a spoke cannot
alone reduce that stress but can only insure that it remain.

Quoted message said:

I would have thought all of the spoke would be at less than yield
throughout the entire build process except for the moment at which
you plastically deform it at the elbow, after which it springs back
a bit, not remaining at yield while you carry on truing and
tensioning etc.

It does not spring back a bit after it is tensioned. As was just
established above, the elbow is yielding as it is bent to an acute
angle and remains there in the absence mechanical stress relief
(overloading it momentarily because it cannot be over-bent beyond
flush to the flange.) A stress relief overload can be applied after
the wheel is built because the rest of the spoke, except for small
regions that were plastically deformed are far below yield stress.

Quoted message said:

Quoted message said:

5. Therefore, adding tension to a spoke cannot relieve that
condition unless an overload is applied and relaxed.

Quoted message said:

I think I follow this, given 4, but 4 is the sticking point.

I hope I cleared that hurdle.

Quoted message said:

Quoted message said:

6. That cyclic loading (as a spoke experiences) at yield stress
causes fatigue failures in spokes.

Quoted message said:

I believe that cyclic loading causes fatigue failures, but don't see
why it has to be at yield stress.

It doesn't need to be but cyclic stress at yield guarantees fatigue
failures, something that is basic to durability in steel. This
underlies the need for stress relief in elements that have been highly
stressed as cold formed spokes are.

Quoted message said:

I realize that generally the higher the mean stress in a stress
cycle, the shorter the number of cycles to failure, so being at
yield stress would certainly exacerbate the problem. But I don't
see how any part of the spokes can be at yield stress in the built
wheel. Yield stress is very high for a steel spoke.

Quoted message said:

Quoted message said:

Quoted message said:

We have heard:

Quoted message said:

Quoted message said:

Quoted message said:

1. Not uncontentious theories explaining why there should be
residual stress.

Quoted message said:

Quoted message said:

I have just reviewed that above.

Quoted message said:

Yes, I appreciate that.

Quoted message said:

Quoted message said:

Quoted message said:

2. Experiments indicating the contrary.

Quoted message said:

Quoted message said:

The experiment does not demonstrate that and there lies the
contention.

Quoted message said:

I agree there's also some contention there, I remember two points:

Quoted message said:

1. Why did the carbon steel spoke bend the wrong way.
2. Does the test need to be performed on a spoke that remains tensioned,
instead of after it's been relaxed?

Quoted message said:

I'm not clear on the reasons for 2, and in spite of 1, I still find the
fact that the spokes clearly unbent on heating unless they were
stress-relieved by modest tensioning quite convincing.

Quoted message said:

Quoted message said:

Quoted message said:

3. Reasonable anecdotal evidence that various processes (squeezing,
the Mavic method, the Trek method) whose supposed effects include
stress-relief reduce spoke failures.

Quoted message said:

Quoted message said:

Yes?

Quoted message said:

Yes!

Quoted message said:

Quoted message said:

Quoted message said:

4. Plenty of other reasons besides presence of residual stress why
spokes might fail.

Quoted message said:

Quoted message said:

Most of which are spurious and given in an effort to prove that there
is no residual stress.

Quoted message said:

Is it spurious to suggest that fatigue might nucleate around surface
cracks and "orange peel" left after forming in poor quality spokes?

Quoted message said:

Is it spurious to believe that spokes that are too loose to the point
that load exceeds pretension in use will suffer premature fatigue
failure because of flexing?

Quoted message said:

[neither are rhetorical questions].

Quoted message said:

Quoted message said:

Quoted message said:

We have not heard:

Quoted message said:

Quoted message said:

Quoted message said:

1. Any evidence that residual stress exists in a newly formed spoke

Quoted message said:

Quoted message said:

Not at all. When a piece of steel is cold formed, as spokes are,
there is always residuals stress. That is why such parts, if
subjected to high loads are thermally stress relieved. The reason
there is residual stress has been explained often in this forum.

Quoted message said:

Fair enough, it has been explained that if you bend a bit of wire it
contains residual stresses, and I can follow that, so unless it's
relieved somehow, some residual stress ought to be present after
forming.

Quoted message said:

[snip]

Quoted message said:

That this condition is reversed if the bend is forcefully held at
maximum curvature should be evident. The surface of the bent spoke is
then in tension on the outside and in compression on the inside of the
bend, from the applied force.

Quoted message said:

Today I bent two lengths of spoke, one of which is kept in tension by
the ends being forced into a keyring, and put both in a jar of saturated
salt water. If anything interesting happens, then I'll put a new spoke
in there too and see if it's possible to detect residual stress at the
elbow using this method.

Quoted message said:

You may be convinced it's there anyway, but it will help some of the
rest of us.

Quoted message said:

Quoted message said:

Quoted message said:

2. or in a spoke just built into a wheel, elbow-corrected and
tensioned.

Quoted message said:

Quoted message said:

Elbow correction is part of stress relieving intended to prevent
cyclic flexing in service but it does not remove the residual stress
caused by that bend operation.

Quoted message said:

Unless normal spoke tensioning serves to relieve the residual stress.

Quoted message said:

Quoted message said:

Quoted message said:

3. Any evidence that residual stress ever contributed to the failure
of a spoke.

Quoted message said:

Quoted message said:

How else do you explain that a spoke that is tensioned to less than
half its yield stress fails at the elbow in a relatively short time?

Quoted message said:

My two top explanations are (a) flexing at the elbow because the spoke's
too loose and the load exceeds its pretension in normal use and (b)
surface imperfections in the elbow in poor quality spokes.

As I said, flexing is part of stress relief by improving the spoke
line. Loose spokes do not accelerate spoke failure. If you believe
so, you should present a mechanism that would cause this.

Quoted message said:

Quoted message said:

It fails because there are high stress points at that place and
that spokes that don't break must have lower stress. The lower
stress is achieved by stress relief and that this is possible by
mechanical means has also been explained in great detail.

Quoted message said:

I do believe it's possible. But so are alien abductions, and I don't
think they happen.

Why don't you believe that is possible?

For example, stretch a spoke with a bend at midspan to yield (as is
done when drawing the wire) and when I performed tensile tests on
spokes, and release it. The spoke will be as straight as imaginable
and its entire cross section will be uniformly at zero stress even
though it originally had a bend in it with residual stress, as was
explained ignoring threads and elbow in order to isolate the process.

Yielding the material will bring it to uniform stress throughout and
relaxing to zero will leave a uniformly stressed wire. with no tensile
stress. If you slice this even finer, radially there may be small
residual radial stresses that do not materially affect tensile loads.
The magnitude and orientation of these stresses are insignificant for a
wire. If that weren't so we could have few cables or wires to carry
loads.

Quoted message said:

Quoted message said:

Quoted message said:

I don't see how we are expected to draw any other conclusion from
this than that as far as we can tell residual stress is unlikely to
be related to spoke failure.

Quoted message said:

Quoted message said:

That is what I find so inexplicable in this discussion. On the one
hand, detailed explanations seem to be too cryptic to understand

Quoted message said:

Certainly I don't understand some of your explanations, mainly point
4 above:

Quoted message said:

Quoted message said:

4. That adding tension to the spoke guarantees that the stress at
the outside of the elbow remains at yield, that being the
highest load it can withstand.

Quoted message said:

and what's wrong with the other explanations for spoke failure.

They lie remote possibilities as causes of failures in these spokes,
and I take DT as the prime example, they having one of the best wire
suppliers and have been working on reliability as long as any. Their
wire is not full of random flaws and other chemical anomalies cited as
spoke failure causes under the guise of metallurgical jargon. If that
were so, there would be systematic failure of their spokes and not
only at the elbow and threads. In contrast, DT spokes (and other good
spokes) still fail on poorly built wheels.

Don't lose sight of Richard Feynman's classic comment: "If you can't
explain it in plain English, you don't understand it yourself."

What is poor about these wheels???? Their build! Failure to improve
spoke line and stress relieve.

Jobst Brandt

Quoted message said:

Ben C? said:

Quoted message said:

> [snip]

Quoted message said:

Quoted message said:

>> Your heating experiment was done on a relaxed spoke and does not
>> reveal what the tension was on the outside of an elbow bend, for
>> instance. If you raised your spoke tension to yield stress prior
>> to relaxing it and heating, then it is evidence of stress
>> relieving by momentary over-stress, nothing more.

Quoted message said:

Quoted message said:

> The experiment was intended as evidence of that. But what it
> indicated is that the normal tensioning of a spoke as a wheel is
> built is enough to relieve any residual stresses that might be
> present in the elbow, either from manufacture or introduced during
> the build when correcting the spoke line.

Quoted message said:

Quoted message said:

Hold it! Let's review a few points. Do you not believe that:

Quoted message said:

Quoted message said:

1. A spoke that has been plastically deformed at the elbow has
reached yield stress?

Quoted message said:

I believe that.

Quoted message said:

Quoted message said:

2. That this stress is tensile.

Quoted message said:

Yes, in my understanding when you bend it at the elbow, you are
putting the outside of the bend in tension and compressing the
inside.

Quoted message said:

Quoted message said:

3. That tensioning a spoke does not raise stress in its parts that
have no residual stress to more than half its yield.

Quoted message said:

Yes-- I don't think normal tensioning is enough to yield the spoke,
even at the elbow.

Quoted message said:

Quoted message said:

4. That adding tension to the spoke guarantees that the stress at
the outside of the elbow remains at yield, that being the
highest load it can withstand.

Quoted message said:

I don't understand this.

OK, the outside of the elbow is at yield. Additional tension makes it
stretch while it remains at yield (by definition of yield) the stress
at which the steel stretches. Therefore tensioning a spoke cannot
alone reduce that stress but can only insure that it remain.

that's confused.
1. there's elastic stretching and there's plastic yield.
2. in bending there are regions that yield, and those that don't.
3. tensioning a spoke elbow will /decrease/ stress in some regions where
others decrease.

Quoted message said:

Quoted message said:

I would have thought all of the spoke would be at less than yield
throughout the entire build process except for the moment at which
you plastically deform it at the elbow, after which it springs back
a bit, not remaining at yield while you carry on truing and
tensioning etc.

It does not spring back a bit after it is tensioned.

it most certainly /will/ spring back after it is tensioned!!!
absolutely definitely. if you contest that, you don't understand the
basics.

Quoted message said:

As was just
established above, the elbow is yielding as it is bent to an acute
angle and remains there in the absence mechanical stress relief
(overloading it momentarily because it cannot be over-bent beyond
flush to the flange.)

more confusion. mechanical stress relief is not about forming the spoke!

Quoted message said:

A stress relief overload can be applied after
the wheel is built because the rest of the spoke, except for small
regions that were plastically deformed are far below yield stress.

no! applied stress can be close to yield, especially in bending mode.
spoke crossing points, where they interleave, are not far off yield. do
the math.

Quoted message said:

Quoted message said:

Quoted message said:

5. Therefore, adding tension to a spoke cannot relieve that
condition unless an overload is applied and relaxed.

Quoted message said:

I think I follow this, given 4, but 4 is the sticking point.

I hope I cleared that hurdle.

you would if you opened a book and bothered to read it!

Quoted message said:

Quoted message said:

Quoted message said:

6. That cyclic loading (as a spoke experiences) at yield stress
causes fatigue failures in spokes.

Quoted message said:

I believe that cyclic loading causes fatigue failures, but don't see
why it has to be at yield stress.

It doesn't need to be but cyclic stress at yield guarantees fatigue
failures, something that is basic to durability in steel.

basic to fatigue, not steel. [and there many different types of steel -
something you don't seem to understand given your confusion between
those that strain age and those that don't.]

Quoted message said:

This
underlies the need for stress relief in elements that have been highly
stressed as cold formed spokes are.

no it doesn't. that's a typical jobstian misconception. if you want to
mitigate fatigue, you ensure the design is right, you ensure it's
processed properly, and you use the right material. only after all
that, and if you're sure that residual stress is a problem, do you
bother with mitigation. in highly cold worked wire, that's something of
an academic exercise since the dislocation density is already so high.

Quoted message said:

Quoted message said:

I realize that generally the higher the mean stress in a stress
cycle, the shorter the number of cycles to failure, so being at
yield stress would certainly exacerbate the problem. But I don't
see how any part of the spokes can be at yield stress in the built
wheel. Yield stress is very high for a steel spoke.

Quoted message said:

Quoted message said:

> We have heard:

Quoted message said:

Quoted message said:

> 1. Not uncontentious theories explaining why there should be
> residual stress.

Quoted message said:

Quoted message said:

I have just reviewed that above.

Quoted message said:

Yes, I appreciate that.

Quoted message said:

Quoted message said:

> 2. Experiments indicating the contrary.

Quoted message said:

Quoted message said:

The experiment does not demonstrate that and there lies the
contention.

Quoted message said:

I agree there's also some contention there, I remember two points:

Quoted message said:

1. Why did the carbon steel spoke bend the wrong way.
2. Does the test need to be performed on a spoke that remains tensioned,
instead of after it's been relaxed?

Quoted message said:

I'm not clear on the reasons for 2, and in spite of 1, I still find the
fact that the spokes clearly unbent on heating unless they were
stress-relieved by modest tensioning quite convincing.

Quoted message said:

Quoted message said:

> 3. Reasonable anecdotal evidence that various processes (squeezing,
> the Mavic method, the Trek method) whose supposed effects include
> stress-relief reduce spoke failures.

Quoted message said:

Quoted message said:

Yes?

Quoted message said:

Yes!

Quoted message said:

Quoted message said:

> 4. Plenty of other reasons besides presence of residual stress why
> spokes might fail.

Quoted message said:

Quoted message said:

Most of which are spurious and given in an effort to prove that there
is no residual stress.

Quoted message said:

Is it spurious to suggest that fatigue might nucleate around surface
cracks and "orange peel" left after forming in poor quality spokes?

Quoted message said:

Is it spurious to believe that spokes that are too loose to the point
that load exceeds pretension in use will suffer premature fatigue
failure because of flexing?

Quoted message said:

[neither are rhetorical questions].

Quoted message said:

Quoted message said:

> We have not heard:

Quoted message said:

Quoted message said:

> 1. Any evidence that residual stress exists in a newly formed spoke

Quoted message said:

Quoted message said:

Not at all. When a piece of steel is cold formed, as spokes are,
there is always residuals stress. That is why such parts, if
subjected to high loads are thermally stress relieved. The reason
there is residual stress has been explained often in this forum.

Quoted message said:

Fair enough, it has been explained that if you bend a bit of wire it
contains residual stresses, and I can follow that, so unless it's
relieved somehow, some residual stress ought to be present after
forming.

Quoted message said:

[snip]

Quoted message said:

That this condition is reversed if the bend is forcefully held at
maximum curvature should be evident. The surface of the bent spoke is
then in tension on the outside and in compression on the inside of the
bend, from the applied force.

Quoted message said:

Today I bent two lengths of spoke, one of which is kept in tension by
the ends being forced into a keyring, and put both in a jar of saturated
salt water. If anything interesting happens, then I'll put a new spoke
in there too and see if it's possible to detect residual stress at the
elbow using this method.

[jack of jobst response noted.]

Quoted message said:

Quoted message said:

You may be convinced it's there anyway, but it will help some of the
rest of us.

Quoted message said:

Quoted message said:

> 2. or in a spoke just built into a wheel, elbow-corrected and
> tensioned.

Quoted message said:

Quoted message said:

Elbow correction is part of stress relieving intended to prevent
cyclic flexing in service but it does not remove the residual stress
caused by that bend operation.

Quoted message said:

Unless normal spoke tensioning serves to relieve the residual stress.

Quoted message said:

Quoted message said:

> 3. Any evidence that residual stress ever contributed to the failure
> of a spoke.

Quoted message said:

Quoted message said:

How else do you explain that a spoke that is tensioned to less than
half its yield stress fails at the elbow in a relatively short time?

Quoted message said:

My two top explanations are (a) flexing at the elbow because the spoke's
too loose and the load exceeds its pretension in normal use and (b)
surface imperfections in the elbow in poor quality spokes.

As I said, flexing is part of stress relief by improving the spoke
line. Loose spokes do not accelerate spoke failure.

really???!!!

Quoted message said:

If you believe
so, you should present a mechanism that would cause this.

jobst, when you argue that butted spokes are superior in fatigue, you
are arguing that the increased elasticity prevents spokes going slack
and thereby reducing fatigue. it's all in your book.

Quoted message said:

Quoted message said:

Quoted message said:

It fails because there are high stress points at that place and
that spokes that don't break must have lower stress. The lower
stress is achieved by stress relief and that this is possible by
mechanical means has also been explained in great detail.

Quoted message said:

I do believe it's possible. But so are alien abductions, and I don't
think they happen.

Why don't you believe that is possible?

For example, stretch a spoke with a bend at midspan to yield (as is
done when drawing the wire) and when I performed tensile tests on
spokes, and release it. The spoke will be as straight as imaginable
and its entire cross section will be uniformly at zero stress even
though it originally had a bend in it with residual stress, as was
explained ignoring threads and elbow in order to isolate the process.

it straightens because it yields! duh.

Quoted message said:

Yielding the material will bring it to uniform stress throughout

no. stresses resolve hydrostatically. that's why ductile tensile
fracture surfaces have the "cup and cone" feature.
http://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/exper/bailey/www/fig6.jpg

jeepers jobst, that's a *huge* misconception.

Quoted message said:

and
relaxing to zero will leave a uniformly stressed wire.

no. see above. there's /way/ more to deformation than you're assuming
here.

Quoted message said:

with no tensile
stress. If you slice this even finer, radially there may be small
residual radial stresses that do not materially affect tensile loads.

residual stress has /nothing/ do do with load!!!

Quoted message said:

The magnitude and orientation of these stresses are insignificant for a
wire.

rubbish - they're fundamental to deformation and failure of each strand
- the means by which rope breaks.

Quoted message said:

If that weren't so we could have few cables or wires to carry
loads.

simplistic mistaken nonsense.

Quoted message said:

Quoted message said:

Quoted message said:

> I don't see how we are expected to draw any other conclusion from
> this than that as far as we can tell residual stress is unlikely to
> be related to spoke failure.

Quoted message said:

Quoted message said:

That is what I find so inexplicable in this discussion. On the one
hand, detailed explanations seem to be too cryptic to understand

Quoted message said:

Certainly I don't understand some of your explanations, mainly point
4 above:

Quoted message said:

Quoted message said:

4. That adding tension to the spoke guarantees that the stress at
the outside of the elbow remains at yield, that being the
highest load it can withstand.

Quoted message said:

and what's wrong with the other explanations for spoke failure.

They lie remote possibilities as causes of failures in these spokes,

"remote possibilities"!!! if you knew about fatigue, you might
understand how stupid that statement is!

Quoted message said:

and I take DT as the prime example, they having one of the best wire
suppliers and have been working on reliability as long as any. Their
wire is not full of random flaws and other chemical anomalies cited as
spoke failure causes under the guise of metallurgical jargon.

that's rich!

Quoted message said:

If that
were so, there would be systematic failure of their spokes and not
only at the elbow and threads.

rubbish. spoke fatigue initiates at the point of maximum stress.
maximum stress is caused either by a riser or by an applied load.
risers have many forms. applied is caused by mechanical configuration,
in this case by having load applied off-axis via an offset shank and elbow.

Quoted message said:

In contrast, DT spokes (and other good
spokes) still fail on poorly built wheels.

including your very own "stress relieved" wheels.

Quoted message said:

Don't lose sight of Richard Feynman's classic comment: "If you can't
explain it in plain English, you don't understand it yourself."

what relevance is that to someone that is not only trying to tell us a
good deal more than they actually understand, but won't bother to do any
homework. no amount of "plain english" can cover that kind of stupidity.

Quoted message said:

What is poor about these wheels???? Their build! Failure to improve
spoke line and stress relieve.

bending spokes can increase residual stress, increase surface defects,
increase dislocation density, and if performed prematurely, lead to
spoke alignment issues since the spoke is being forced to conform with a
hub not yet yielded to its final shape. maybe that's why manufacturers
specifically say not to do it. but how would they know - they only do
research - such a waste when they could make under-informed assumptions
and save themselves so much money and effort. incidentally, when are
you going to perform your residual stress testing?

On Sun, 31 Dec 2006 16:55:22 -0800, jim beam wrote: <snip>

Quoted message said:

bending spokes can increase residual stress, increase surface defects,
increase dislocation density, and if performed prematurely, lead to
spoke alignment issues since the spoke is being forced to conform with a
hub not yet yielded to its final shape. maybe that's why manufacturers
specifically say not to do it.

As you should know, since it's been pointed out to you before, Bontrager
recommends correcting the spoke lines on its wheels:

http://tinyurl.com/7fkbv (pdf) -- see page 7.

Gerd Schrander, whose book (the German edition) is sold by DT and touted
on its website, recommends correcting the spoke line:

"Another small job simply involves bending the spokes at the nipple ends -
the misalignment of spoke and nipple depends on the number of spokes and
the spoking method used. Hold crossed pairs of spokes and squeeze them
together. The spokes are made of flexible wire and so bending them in this
way does no harm whatsoever."

Page 85 of the English edition.

Eric Hjertberg, one of the founders of Wheelsmith, recommends correcting
the spoke line:

"Now that each spoke is adjusted to the same length as its neighbors, it's
time to bend the spokes near their elbow so they fully conform to their
direction. Do it by inserting a stout screwdriver shaft between two
spokes, just under one of the crosses. Once in this triangle, lever the
screwdriver so the handle end rests against the outside spoke and the
blade end presses against the inside spoke. A gentle push will bend them
into conformity. Go around the wheel "setting in" pairs. This procedure
stabilizes the wheel by doing immediately what normally occurs during
miles of riding. The life of each spoke is enhanced because each elbow
bends less after it conforms to its path. Otherwise, it constantly tries
to recover its original shape during riding and fatigues more quickly."

www.crazyrides.com/en/mastermechanic/part2.htm

The only evidence I see that manufacturers frown on correcting the spoke
line is a Sapim FAQ that's riddled with errors.

Do you have some other evidence?

Gary Young said:

On Sun, 31 Dec 2006 16:55:22 -0800, jim beam wrote: <snip>

Quoted message said:

bending spokes can increase residual stress, increase surface defects,
increase dislocation density, and if performed prematurely, lead to
spoke alignment issues since the spoke is being forced to conform with a
hub not yet yielded to its final shape. maybe that's why manufacturers
specifically say not to do it.

As you should know, since it's been pointed out to you before, Bontrager
recommends correcting the spoke lines on its wheels:

http://tinyurl.com/7fkbv (pdf) -- see page 7.

Gerd Schrander, whose book (the German edition) is sold by DT and touted
on its website, recommends correcting the spoke line:

"Another small job simply involves bending the spokes at the nipple ends -
the misalignment of spoke and nipple depends on the number of spokes and
the spoking method used. Hold crossed pairs of spokes and squeeze them
together. The spokes are made of flexible wire and so bending them in this
way does no harm whatsoever."

Page 85 of the English edition.

Eric Hjertberg, one of the founders of Wheelsmith, recommends correcting
the spoke line:

"Now that each spoke is adjusted to the same length as its neighbors, it's
time to bend the spokes near their elbow so they fully conform to their
direction. Do it by inserting a stout screwdriver shaft between two
spokes, just under one of the crosses. Once in this triangle, lever the
screwdriver so the handle end rests against the outside spoke and the
blade end presses against the inside spoke. A gentle push will bend them
into conformity. Go around the wheel "setting in" pairs. This procedure
stabilizes the wheel by doing immediately what normally occurs during
miles of riding. The life of each spoke is enhanced because each elbow
bends less after it conforms to its path. Otherwise, it constantly tries
to recover its original shape during riding and fatigues more quickly."

www.crazyrides.com/en/mastermechanic/part2.htm

The only evidence I see that manufacturers frown on correcting the spoke
line is a Sapim FAQ that's riddled with errors.

Do you have some other evidence?

let me repeat:
"bending spokes can increase residual stress, increase surface defects,
increase dislocation density, and if performed prematurely, lead to
spoke alignment issues since the spoke is being forced to conform with a
hub not yet yielded to its final shape."

any questions?

regarding your citations, none bar wheelsmith are spoke manufacturers -
they simply assemble wheels from components they buy in. it's also
worth noting that bontrager have been savaged by jobst over the years,
schraner has been excoriated for saying that hubs hang from upper
spokes, and hjertberg is a buddy of jobst. i don't know wheelsmith's
position on this, but since they tend to be a little coy with details
such as how exactly their spokes are made, they may be choosing to swim
with the tide rather than fight against entrenched jobstian myopia.

there are countless other cases of people mindlessly repeating jobstian
drivel. example: increasing spoke tension increases wheel strength,
rims crack because of anodizing, fatigue can be eliminated by "stress
relief", etc. but all i see that repetition proving is the willingness
of people to believe and take on faith rather than question and seek
fact. did /you/ notice any of jobst's errors in his book? if not, then
you're likely to repeat them too.

an anonymous former metallurgist said:

Quoted message said:

Quoted message said:

>> [snip]

Quoted message said:

Quoted message said:

Quoted message said:

>>> Your heating experiment was done on a relaxed spoke and does
>>> not reveal what the tension was on the outside of an elbow
>>> bend, for instance. If you raised your spoke tension to yield
>>> stress prior to relaxing it and heating, then it is evidence of
>>> stress relieving by momentary over-stress, nothing more.

Quoted message said:

Quoted message said:

Quoted message said:

>> The experiment was intended as evidence of that. But what it
>> indicated is that the normal tensioning of a spoke as a wheel is
>> built is enough to relieve any residual stresses that might be
>> present in the elbow, either from manufacture or introduced
>> during the build when correcting the spoke line.

Quoted message said:

Quoted message said:

Quoted message said:

> Hold it! Let's review a few points. Do you not believe that:

Quoted message said:

Quoted message said:

Quoted message said:

> 1. A spoke that has been plastically deformed at the elbow has
> reached yield stress?

Quoted message said:

Quoted message said:

Quoted message said:

I believe that.

Quoted message said:

Quoted message said:

Quoted message said:

> 2. That this stress is tensile.

Quoted message said:

Quoted message said:

Quoted message said:

Yes, in my understanding when you bend it at the elbow, you are
putting the outside of the bend in tension and compressing the
inside.

Quoted message said:

Quoted message said:

Quoted message said:

> 3. That tensioning a spoke does not raise stress in its parts
> that have no residual stress to more than half its yield.

Quoted message said:

Quoted message said:

Quoted message said:

Yes-- I don't think normal tensioning is enough to yield the
spoke, even at the elbow.

Quoted message said:

Quoted message said:

Quoted message said:

> 4. That adding tension to the spoke guarantees that the stress at
> the outside of the elbow remains at yield, that being the
> highest load it can withstand.

Quoted message said:

Quoted message said:

Quoted message said:

I don't understand this.

Quoted message said:

Quoted message said:

OK, the outside of the elbow is at yield. Additional tension makes
it stretch while it remains at yield (by definition of yield) the
stress at which the steel stretches. Therefore tensioning a spoke
cannot alone reduce that stress but can only insure that it remain.

Quoted message said:

that's confused.
1. there's elastic stretching and there's plastic yield.
2. in bending there are regions that yield, and those that don't.
3. tensioning a spoke elbow will /decrease/ stress in some regions
where others decrease.

Not when a spoke section is already at yield. Outbound spokes deform
plastically at the elbow while being pulled flush against the flange
by tensioning or by manual action. In either event, the outside of
the elbow is at yield stress. This is about residual high stress, not
about areas that are relaxed by tensioning, as on the inside of elbows
for instance.

Quoted message said:

Quoted message said:

Quoted message said:

I would have thought all of the spoke would be at less than yield
throughout the entire build process except for the moment at which
you plastically deform it at the elbow, after which it springs
back a bit, not remaining at yield while you carry on truing and
tensioning etc.

Quoted message said:

Quoted message said:

It does not spring back a bit after it is tensioned.

Quoted message said:

it most certainly /will/ spring back after it is tensioned!!!
absolutely definitely. if you contest that, you don't understand
the basics.

A spoke cannot spring back permanently if it remains tensioned. It is
that spring back during cyclic unloading that needs to be reduced by
stress relieving. If it weren't under residual stress, it would not
spring back.

Quoted message said:

Quoted message said:

As was just was established above, the elbow is yielding as it is
bent to an acute angle and remains there in the absence mechanical
stress relief (overloading it momentarily because it cannot be
over-bent beyond flush to the flange.)

Quoted message said:

more confusion. mechanical stress relief is not about forming the
spoke!

It IS about forming the spoke at the elbow because even though it
might seem to be static, as mentioned above, it springs back from
residual stress. Overloading tension in the outer radius yields that
area and gives it a form that does not flex with each wheel rotation.

Quoted message said:

Quoted message said:

A stress relief overload can be applied after the wheel is built
because the rest of the spoke, except for small regions that were
plastically deformed are far below yield stress.

Quoted message said:

no! applied stress can be close to yield, especially in bending
mode. spoke crossing points, where they interleave, are not far off
yield. do the math.

Forget about spoke crossings, a red herring for sure, considering that
there are no fatigue failure reports for that part of the spoke.

Quoted message said:

Quoted message said:

Quoted message said:

> 5. Therefore, adding tension to a spoke cannot relieve that
> condition unless an overload is applied and relaxed.

Quoted message said:

Quoted message said:

Quoted message said:

I think I follow this, given 4, but 4 is the sticking point.

Quoted message said:

Quoted message said:

I hope I cleared that hurdle.

Quoted message said:

you would if you opened a book and bothered to read it!

Quoted message said:

Quoted message said:

Quoted message said:

> 6. That cyclic loading (as a spoke experiences) at yield stress
> causes fatigue failures in spokes.

Quoted message said:

Quoted message said:

Quoted message said:

I believe that cyclic loading causes fatigue failures, but don't
see why it has to be at yield stress.

Quoted message said:

Quoted message said:

It doesn't need to be but cyclic stress at yield guarantees fatigue
failures, something that is basic to durability in steel.

Quoted message said:

basic to fatigue, not steel. [and there many different types of
steel - something you don't seem to understand given your confusion
between those that strain age and those that don't.]

We happen to be talking of stainless steel spokes. Omitting the word
steel would certainly evoke spurious references to materials with
other characteristics from you.

Quoted message said:

Quoted message said:

This underlies the need for stress relief in elements that have
been highly stressed as cold formed spokes are.

Quoted message said:

no it doesn't. that's a typical jobstian misconception. if you
want to mitigate fatigue, you ensure the design is right, you ensure
it's processed properly, and you use the right material. only after
all that, and if you're sure that residual stress is a problem, do
you bother with mitigation. in highly cold worked wire, that's
something of an academic exercise since the dislocation density is
already so high.

I see you deny that residual stress from forming the spoke and lacing
it into a wheel have an effect on fatigue failures. In that event,
you might explain how poorly built wheels have spoke failures while
others do not. One might get the impression that the wheel builder
has no control over spoke durability.

Quoted message said:

Quoted message said:

Quoted message said:

I realize that generally the higher the mean stress in a stress
cycle, the shorter the number of cycles to failure, so being at
yield stress would certainly exacerbate the problem. But I don't
see how any part of the spokes can be at yield stress in the built
wheel. Yield stress is very high for a steel spoke.

Quoted message said:

Quoted message said:

Quoted message said:

>> We have heard:

Quoted message said:

Quoted message said:

Quoted message said:

>> 1. Not uncontentious theories explaining why there should be
>> residual stress.

Quoted message said:

Quoted message said:

Quoted message said:

> I have just reviewed that above.

Quoted message said:

Quoted message said:

Quoted message said:

Yes, I appreciate that.

Quoted message said:

Quoted message said:

Quoted message said:

>> 2. Experiments indicating the contrary.

Quoted message said:

Quoted message said:

Quoted message said:

> The experiment does not demonstrate that and there lies the
> contention.

Quoted message said:

Quoted message said:

Quoted message said:

I agree there's also some contention there, I remember two points:

Quoted message said:

Quoted message said:

Quoted message said:

1. Why did the carbon steel spoke bend the wrong way.

Quoted message said:

Quoted message said:

Quoted message said:

2. Does the test need to be performed on a spoke that remains
tensioned, instead of after it's been relaxed?

Quoted message said:

Quoted message said:

Quoted message said:

I'm not clear on the reasons for 2, and in spite of 1, I still
find the fact that the spokes clearly unbent on heating unless
they were stress-relieved by modest tensioning quite convincing.

Quoted message said:

Quoted message said:

Quoted message said:

>> 3. Reasonable anecdotal evidence that various processes
>> (squeezing, the Mavic method, the Trek method) whose supposed
>> effects include stress-relief reduce spoke failures.

Quoted message said:

Quoted message said:

Quoted message said:

> Yes?

Quoted message said:

Quoted message said:

Quoted message said:

Yes!

Quoted message said:

Quoted message said:

Quoted message said:

>> 4. Plenty of other reasons besides presence of residual stress
>> why spokes might fail.

Quoted message said:

Quoted message said:

Quoted message said:

> Most of which are spurious and given in an effort to prove that
> there is no residual stress.

Quoted message said:

Quoted message said:

Quoted message said:

Is it spurious to suggest that fatigue might nucleate around
surface cracks and "orange peel" left after forming in poor
quality spokes?

Quoted message said:

Quoted message said:

Quoted message said:

Is it spurious to believe that spokes that are too loose to the
point that load exceeds pretension in use will suffer premature
fatigue failure because of flexing?

Quoted message said:

Quoted message said:

Quoted message said:

[neither are rhetorical questions].

Quoted message said:

Quoted message said:

Quoted message said:

>> We have not heard:

Quoted message said:

Quoted message said:

Quoted message said:

>> 1. Any evidence that residual stress exists in a newly formed
>> spoke

Quoted message said:

Quoted message said:

Quoted message said:

> Not at all. When a piece of steel is cold formed, as spokes are,
> there is always residuals stress. That is why such parts, if
> subjected to high loads are thermally stress relieved. The
> reason there is residual stress has been explained often in this
> forum.

Quoted message said:

Quoted message said:

Quoted message said:

Fair enough, it has been explained that if you bend a bit of wire
it contains residual stresses, and I can follow that, so unless
it's relieved somehow, some residual stress ought to be present
after forming.

Quoted message said:

Quoted message said:

Quoted message said:

[snip]

Quoted message said:

Quoted message said:

Quoted message said:

> That this condition is reversed if the bend is forcefully held at
> maximum curvature should be evident. The surface of the bent
> spoke is then in tension on the outside and in compression on the
> inside of the bend, from the applied force.

Quoted message said:

Quoted message said:

Quoted message said:

Today I bent two lengths of spoke, one of which is kept in tension
by the ends being forced into a keyring, and put both in a jar of
saturated salt water. If anything interesting happens, then I'll
put a new spoke in there too and see if it's possible to detect
residual stress at the elbow using this method.

Quoted message said:

[jack of jobst response noted.]

Quoted message said:

Quoted message said:

Quoted message said:

You may be convinced it's there anyway, but it will help some of
the rest of us.

Quoted message said:

Quoted message said:

Quoted message said:

>> 2. or in a spoke just built into a wheel, elbow-corrected and
>> tensioned.

Quoted message said:

Quoted message said:

Quoted message said:

> Elbow correction is part of stress relieving intended to prevent
> cyclic flexing in service but it does not remove the residual
> stress caused by that bend operation.

Quoted message said:

Quoted message said:

Quoted message said:

Unless normal spoke tensioning serves to relieve the residual
stress.

Quoted message said:

Quoted message said:

Quoted message said:

>> 3. Any evidence that residual stress ever contributed to the
>> failure of a spoke.

Quoted message said:

Quoted message said:

Quoted message said:

> How else do you explain that a spoke that is tensioned to less
> than half its yield stress fails at the elbow in a relatively
> short time?

Quoted message said:

Quoted message said:

Quoted message said:

My two top explanations are (a) flexing at the elbow because the
spoke's too loose and the load exceeds its pretension in normal
use and (b) surface imperfections in the elbow in poor quality
spokes.

Quoted message said:

Quoted message said:

As I said, flexing is part of stress relief by improving the spoke
line. Loose spokes do not accelerate spoke failure.

Quoted message said:

really???!!!

Quoted message said:

Quoted message said:

If you believe so, you should present a mechanism that would cause
this.

Quoted message said:

jobst, when you argue that butted spokes are superior in fatigue,
you are arguing that the increased elasticity prevents spokes going
slack and thereby reducing fatigue. it's all in your book.

I presented the case for buttes spoke to be more elastic and
distribute loads over a greater number of spokes. You may have
interpreted that to your beliefs, but it isn't there. I do not
attribute fatigue failures to slackening.

Quoted message said:

Quoted message said:

Quoted message said:

> It fails because there are high stress points at that place and
> that spokes that don't break must have lower stress. The lower
> stress is achieved by stress relief and that this is possible by
> mechanical means has also been explained in great detail.

Quoted message said:

Quoted message said:

Quoted message said:

I do believe it's possible. But so are alien abductions, and I
don't think they happen.

Quoted message said:

Quoted message said:

Why don't you believe that is possible?

Quoted message said:

Quoted message said:

For example, stretch a spoke with a bend at midspan to yield (as is
done when drawing the wire) and when I performed tensile tests on
spokes, and release it. The spoke will be as straight as
imaginable and its entire cross section will be uniformly at zero
stress even though it originally had a bend in it with residual
stress, as was explained ignoring threads and elbow in order to
isolate the process.

Quoted message said:

it straightens because it yields! duh.

Quoted message said:

Quoted message said:

Yielding the material will bring it to uniform stress throughout
and relaxing to zero will leave a uniformly stressed wire.

Quoted message said:

no. stresses resolve hydrostatically. that's why ductile tensile
fracture surfaces have the "cup and cone" feature.

http://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/exper/bailey/www/fig6.jpg

Quoted message said:

jeepers jobst, that's a *huge* misconception.

Maybe you can explain what your reference is demonstrating. This is
apparently not a fatigue failure and not on a spoke. I don't see what
this has to do with the sentence above the reply.

Quoted message said:

no. see above. there's /way/ more to deformation than you're assuming
here.

Don't keep it a secret.

Quoted message said:

Quoted message said:

with no tensile stress. If you slice this even finer, radially
there may be small residual radial stresses that do not materially
affect tensile loads.

Quoted message said:

residual stress has /nothing/ do do with load!!!

Fatigue failures have much to do with residual stress overlayed on
cyclic operational loads. Looking out of the box makes it difficult
to see what's in the box, and residual stress along with working loads
are the problem.

Quoted message said:

Quoted message said:

The magnitude and orientation of these stresses are insignificant
for a wire.

Quoted message said:

rubbish - they're fundamental to deformation and failure of each
strand - the means by which rope breaks.

OH! That must be why spokes don't fail at midspan even though they
have been deformed. There aren't high enough stresses remaining in
the spoke, even in its reduced cross section to cause fatigue failure.

Quoted message said:

Quoted message said:

If that weren't so we could have few cables or wires to carry
loads.

Quoted message said:

simplistic mistaken nonsense.

I don't see an explanation for your point of view.

Quoted message said:

Quoted message said:

Quoted message said:

>> I don't see how we are expected to draw any other conclusion
>> from this than that as far as we can tell residual stress is
>> unlikely to be related to spoke failure.

Quoted message said:

Quoted message said:

Quoted message said:

> That is what I find so inexplicable in this discussion. On the
> one hand, detailed explanations seem to be too cryptic to
> understand

Quoted message said:

Quoted message said:

Quoted message said:

Certainly I don't understand some of your explanations, mainly
point 4 above:

Quoted message said:

Quoted message said:

Quoted message said:

> 4. That adding tension to the spoke guarantees that the stress at
> the outside of the elbow remains at yield, that being the
> highest load it can withstand.

Quoted message said:

Quoted message said:

Quoted message said:

and what's wrong with the other explanations for spoke failure.

Quoted message said:

Quoted message said:

They lie as remote possibilities as causes of failures in these
spokes,

Quoted message said:

"remote possibilities"!!! if you knew about fatigue, you might
understand how stupid that statement is!

Thanks again.

Quoted message said:

Quoted message said:

and I take DT as the prime example, they having one of the best
wire suppliers and have been working on reliability as long as any.
Their wire is not full of random flaws and other chemical anomalies
cited as spoke failure causes under the guise of metallurgical
jargon.

Quoted message said:

that's rich!

Quoted message said:

Quoted message said:

If that were so, there would be systematic failure of their spokes
and not only at the elbow and threads.

Quoted message said:

rubbish. spoke fatigue initiates at the point of maximum stress.
maximum stress is caused either by a riser or by an applied load.
risers have many forms. applied is caused by mechanical
configuration, in this case by having load applied off-axis via an
offset shank and elbow.

So why are these failures concentrated at points that have stress up
to yield as at outside of elbows and at the root of threads. One
might deduce that the manufacturer knowingly concentrates these
anomalies at those points to support the theory of no residual stress.

Quoted message said:

Quoted message said:

In contrast, DT spokes (and other good spokes) still fail on poorly
built wheels.

Quoted message said:

including your very own "stress relieved" wheels.

Thanks again. You know that is untrue but toss it out just the same.

Quoted message said:

Quoted message said:

Don't lose sight of Richard Feynman's classic comment: "If you
can't explain it in plain English, you don't understand it
yourself."

Quoted message said:

what relevance is that to someone that is not only trying to tell us
a good deal more than they actually understand, but won't bother to
do any homework. no amount of "plain english" can cover that kind
of stupidity.

Quoted message said:

Quoted message said:

What is poor about these wheels???? Their build! Failure to
improve spoke line and stress relieve.

Quoted message said:

bending spokes can increase residual stress, increase surface
defects, increase dislocation density, and if performed prematurely,
lead to spoke alignment issues since the spoke is being forced to
conform with a hub not yet yielded to its final shape. maybe that's
why manufacturers specifically say not to do it. but how would they
know - they only do research - such a waste when they could make
under-informed assumptions and save themselves so much money and
effort. incidentally, when are you going to perform your residual
stress testing?

When are you going to explain what occurs in wheel building that will
build more durable wheels and prevent spoke failures? You seem to
believe that it is solely my duty to test every hypothesis that can be
presented on the subject here on wreck.bike.

Jobst Brandt

Quoted message said:

It IS about forming the spoke at the elbow because even though it
might seem to be static, as mentioned above, it springs back from
residual stress. Overloading tension in the outer radius yields that
area and gives it a form that does not flex with each wheel rotation.

Makes me wonder what danger there would be in *over* bending the elbow
to conform to the hub. Seems like this would be preferable...

The Eric Hjertberg method of bending the spokes around with a screw
driver *inside* the crossing would certainly achieve this.

I just rebuilt a wheel, resuing 1.8/1.55mm spokes that previously had
DT washers under the heads. Some of the washers cracked in two when I
moved the spokes, so I decided to get rid of them... only now the
spokes are not shaped to fit the hub so well. I bent the spokes inside
the cross (2x 32 hole) using a srew driver, *after* the wheel was fully
tensioned, so that now the J resembles the the hook that goes on the
end of chains... ie the spoke wraps around the flange a bit, and the
center of the spoke line for both inside and outside spokes heads to
the center of the hub flange. Comments?

Quoted message said:

an anonymous former metallurgist said:

Quoted message said:

>>> [snip]

Quoted message said:

Quoted message said:

>>>> Your heating experiment was done on a relaxed spoke and does
>>>> not reveal what the tension was on the outside of an elbow
>>>> bend, for instance. If you raised your spoke tension to yield
>>>> stress prior to relaxing it and heating, then it is evidence of
>>>> stress relieving by momentary over-stress, nothing more.

Quoted message said:

Quoted message said:

>>> The experiment was intended as evidence of that. But what it
>>> indicated is that the normal tensioning of a spoke as a wheel is
>>> built is enough to relieve any residual stresses that might be
>>> present in the elbow, either from manufacture or introduced
>>> during the build when correcting the spoke line.

Quoted message said:

Quoted message said:

>> Hold it! Let's review a few points. Do you not believe that:

Quoted message said:

Quoted message said:

>> 1. A spoke that has been plastically deformed at the elbow has
>> reached yield stress?

Quoted message said:

Quoted message said:

> I believe that.

Quoted message said:

Quoted message said:

>> 2. That this stress is tensile.

Quoted message said:

Quoted message said:

> Yes, in my understanding when you bend it at the elbow, you are
> putting the outside of the bend in tension and compressing the
> inside.

Quoted message said:

Quoted message said:

>> 3. That tensioning a spoke does not raise stress in its parts
>> that have no residual stress to more than half its yield.

Quoted message said:

Quoted message said:

> Yes-- I don't think normal tensioning is enough to yield the
> spoke, even at the elbow.

Quoted message said:

Quoted message said:

>> 4. That adding tension to the spoke guarantees that the stress at
>> the outside of the elbow remains at yield, that being the
>> highest load it can withstand.

Quoted message said:

Quoted message said:

> I don't understand this.

Quoted message said:

Quoted message said:

OK, the outside of the elbow is at yield. Additional tension makes
it stretch while it remains at yield (by definition of yield) the
stress at which the steel stretches. Therefore tensioning a spoke
cannot alone reduce that stress but can only insure that it remain.

Quoted message said:

that's confused.
1. there's elastic stretching and there's plastic yield.
2. in bending there are regions that yield, and those that don't.
3. tensioning a spoke elbow will /decrease/ stress in some regions
where others decrease.

Not when a spoke section is already at yield. Outbound spokes deform
plastically at the elbow while being pulled flush against the flange
by tensioning or by manual action. In either event, the outside of
the elbow is at yield stress.

you can't have it both ways jobst. according to you, the outside of the
elbow has compressive residual. let's say that's 20% of yield. if we
now bend to that with no residual, it would be at yield, resultant is
that it's at only 80% of yield.

but even that is not true. empirical results show that the spoke
operates well below yield since it does not immediately fail. high
cycle fatigue, that observed from fracture surface examination, rarely
occurs below 10^3 cycles, and that is going to be well below yield.

Quoted message said:

This is about residual high stress, not
about areas that are relaxed by tensioning, as on the inside of elbows
for instance.

that's a minor part of the equation jobst. you can read that for
yourself in the library. surface finish quality is a /much/ bigger factor.
http://www.flickr.com/photos/38636024@N00/340348242/
deiter - mechanical metallurgy
from the accompanying text:
"the extreme sensitivity of high strength steel to surface conditions is
well illustrated". they're not kidding. that's why stainless steel,
despite the fact that it has no endurance limit, is a successful spoke
material, especially for quality spokes with a good quality finish.

Quoted message said:

Quoted message said:

Quoted message said:

> I would have thought all of the spoke would be at less than yield
> throughout the entire build process except for the moment at which
> you plastically deform it at the elbow, after which it springs
> back a bit, not remaining at yield while you carry on truing and
> tensioning etc.

Quoted message said:

Quoted message said:

It does not spring back a bit after it is tensioned.

Quoted message said:

it most certainly /will/ spring back after it is tensioned!!!
absolutely definitely. if you contest that, you don't understand
the basics.

A spoke cannot spring back permanently if it remains tensioned.

fudge.

Quoted message said:

It is
that spring back during cyclic unloading that needs to be reduced by
stress relieving.

it cannot - the whole structure is elastic.

Quoted message said:

If it weren't under residual stress, it would not
spring back.

jobst, that is such an incredible fundamental misconception, i'm slack
jawed with amazement. seriously, if you have problems with the
concepts, i'll copy and send you material you can read to educate
yourself. in the mean time, please don't repeat such mistakes - you'll
keep getting yourself into big trouble with the rest of your
comprehension of fatigue, deformation, the whole works.

Quoted message said:

Quoted message said:

Quoted message said:

As was just was established above, the elbow is yielding as it is
bent to an acute angle and remains there in the absence mechanical
stress relief (overloading it momentarily because it cannot be
over-bent beyond flush to the flange.)

Quoted message said:

more confusion. mechanical stress relief is not about forming the
spoke!

It IS about forming the spoke at the elbow because even though it
might seem to be static, as mentioned above, it springs back from
residual stress.

no it doesn't. see above. it springs back with elasticity. see #3.
http://www.flickr.com/photos/38636024@N00/327752060/

Quoted message said:

Overloading tension in the outer radius yields that
area and gives it a form that does not flex with each wheel rotation.

yes it does. the fact that it fatigued shows that it does.

Quoted message said:

Quoted message said:

Quoted message said:

A stress relief overload can be applied after the wheel is built
because the rest of the spoke, except for small regions that were
plastically deformed are far below yield stress.

Quoted message said:

no! applied stress can be close to yield, especially in bending
mode. spoke crossing points, where they interleave, are not far off
yield. do the math.

Forget about spoke crossings, a red herring for sure, considering that
there are no fatigue failure reports for that part of the spoke.

it's not a herring. the outer part of the crossing bend is in tension
at a level that compares with residual stress, yet it doesn't fatigue.

Quoted message said:

Quoted message said:

Quoted message said:

>> 5. Therefore, adding tension to a spoke cannot relieve that
>> condition unless an overload is applied and relaxed.

Quoted message said:

Quoted message said:

> I think I follow this, given 4, but 4 is the sticking point.

Quoted message said:

Quoted message said:

I hope I cleared that hurdle.

Quoted message said:

you would if you opened a book and bothered to read it!

Quoted message said:

Quoted message said:

>> 6. That cyclic loading (as a spoke experiences) at yield stress
>> causes fatigue failures in spokes.

Quoted message said:

Quoted message said:

> I believe that cyclic loading causes fatigue failures, but don't
> see why it has to be at yield stress.

Quoted message said:

Quoted message said:

It doesn't need to be but cyclic stress at yield guarantees fatigue
failures, something that is basic to durability in steel.

Quoted message said:

basic to fatigue, not steel. [and there many different types of
steel - something you don't seem to understand given your confusion
between those that strain age and those that don't.]

We happen to be talking of stainless steel spokes. Omitting the word
steel would certainly evoke spurious references to materials with
other characteristics from you.

ad hominem doesn't get around the fact that you still don't seem to
grasp the fundamental differences between behaviors in different materials.

Quoted message said:

Quoted message said:

Quoted message said:

This underlies the need for stress relief in elements that have
been highly stressed as cold formed spokes are.

Quoted message said:

no it doesn't. that's a typical jobstian misconception. if you
want to mitigate fatigue, you ensure the design is right, you ensure
it's processed properly, and you use the right material. only after
all that, and if you're sure that residual stress is a problem, do
you bother with mitigation. in highly cold worked wire, that's
something of an academic exercise since the dislocation density is
already so high.

I see you deny that residual stress from forming the spoke and lacing
it into a wheel have an effect on fatigue failures.

jobst, for pity's sake, please please please don't keep assuming that
residual stress causes fatigue. it doesn't. it can accelerate it, but
not if other factors are eliminated. and besides, you /can't/ simple
assume residual stress exists. indeed, fatigue evidence suggests that
it's not.

Quoted message said:

In that event,
you might explain how poorly built wheels have spoke failures while
others do not. One might get the impression that the wheel builder
has no control over spoke durability.

they don't! the spoke manufacturer has that control. if you want to
contend this is all in the hands of the builder [contrary to all
materials theory btw] then you need to do the testing and publish
results. you haven't done that. presumption is not a result!

Quoted message said:

Quoted message said:

Quoted message said:

> I realize that generally the higher the mean stress in a stress
> cycle, the shorter the number of cycles to failure, so being at
> yield stress would certainly exacerbate the problem. But I don't
> see how any part of the spokes can be at yield stress in the built
> wheel. Yield stress is very high for a steel spoke.

Quoted message said:

Quoted message said:

>>> We have heard:

Quoted message said:

Quoted message said:

>>> 1. Not uncontentious theories explaining why there should be
>>> residual stress.

Quoted message said:

Quoted message said:

>> I have just reviewed that above.

Quoted message said:

Quoted message said:

> Yes, I appreciate that.

Quoted message said:

Quoted message said:

>>> 2. Experiments indicating the contrary.

Quoted message said:

Quoted message said:

>> The experiment does not demonstrate that and there lies the
>> contention.

Quoted message said:

Quoted message said:

> I agree there's also some contention there, I remember two points:

Quoted message said:

Quoted message said:

> 1. Why did the carbon steel spoke bend the wrong way.

Quoted message said:

Quoted message said:

> 2. Does the test need to be performed on a spoke that remains
> tensioned, instead of after it's been relaxed?

Quoted message said:

Quoted message said:

> I'm not clear on the reasons for 2, and in spite of 1, I still
> find the fact that the spokes clearly unbent on heating unless
> they were stress-relieved by modest tensioning quite convincing.

Quoted message said:

Quoted message said:

>>> 3. Reasonable anecdotal evidence that various processes
>>> (squeezing, the Mavic method, the Trek method) whose supposed
>>> effects include stress-relief reduce spoke failures.

Quoted message said:

Quoted message said:

>> Yes?

Quoted message said:

Quoted message said:

> Yes!

Quoted message said:

Quoted message said:

>>> 4. Plenty of other reasons besides presence of residual stress
>>> why spokes might fail.

Quoted message said:

Quoted message said:

>> Most of which are spurious and given in an effort to prove that
>> there is no residual stress.

Quoted message said:

Quoted message said:

> Is it spurious to suggest that fatigue might nucleate around
> surface cracks and "orange peel" left after forming in poor
> quality spokes?

Quoted message said:

Quoted message said:

> Is it spurious to believe that spokes that are too loose to the
> point that load exceeds pretension in use will suffer premature
> fatigue failure because of flexing?

Quoted message said:

Quoted message said:

> [neither are rhetorical questions].

Quoted message said:

Quoted message said:

>>> We have not heard:

Quoted message said:

Quoted message said:

>>> 1. Any evidence that residual stress exists in a newly formed
>>> spoke

Quoted message said:

Quoted message said:

>> Not at all. When a piece of steel is cold formed, as spokes are,
>> there is always residuals stress. That is why such parts, if
>> subjected to high loads are thermally stress relieved. The
>> reason there is residual stress has been explained often in this
>> forum.

Quoted message said:

Quoted message said:

> Fair enough, it has been explained that if you bend a bit of wire
> it contains residual stresses, and I can follow that, so unless
> it's relieved somehow, some residual stress ought to be present
> after forming.

Quoted message said:

Quoted message said:

> [snip]

Quoted message said:

Quoted message said:

>> That this condition is reversed if the bend is forcefully held at
>> maximum curvature should be evident. The surface of the bent
>> spoke is then in tension on the outside and in compression on the
>> inside of the bend, from the applied force.

Quoted message said:

Quoted message said:

> Today I bent two lengths of spoke, one of which is kept in tension
> by the ends being forced into a keyring, and put both in a jar of
> saturated salt water. If anything interesting happens, then I'll
> put a new spoke in there too and see if it's possible to detect
> residual stress at the elbow using this method.

Quoted message said:

[jack of jobst response noted.]

Quoted message said:

Quoted message said:

> You may be convinced it's there anyway, but it will help some of
> the rest of us.

Quoted message said:

Quoted message said:

>>> 2. or in a spoke just built into a wheel, elbow-corrected and
>>> tensioned.

Quoted message said:

Quoted message said:

>> Elbow correction is part of stress relieving intended to prevent
>> cyclic flexing in service but it does not remove the residual
>> stress caused by that bend operation.

Quoted message said:

Quoted message said:

> Unless normal spoke tensioning serves to relieve the residual
> stress.

Quoted message said:

Quoted message said:

>>> 3. Any evidence that residual stress ever contributed to the
>>> failure of a spoke.

Quoted message said:

Quoted message said:

>> How else do you explain that a spoke that is tensioned to less
>> than half its yield stress fails at the elbow in a relatively
>> short time?

Quoted message said:

Quoted message said:

> My two top explanations are (a) flexing at the elbow because the
> spoke's too loose and the load exceeds its pretension in normal
> use and (b) surface imperfections in the elbow in poor quality
> spokes.

Quoted message said:

Quoted message said:

As I said, flexing is part of stress relief by improving the spoke
line. Loose spokes do not accelerate spoke failure.

Quoted message said:

really???!!!

Quoted message said:

Quoted message said:

If you believe so, you should present a mechanism that would cause
this.

Quoted message said:

jobst, when you argue that butted spokes are superior in fatigue,
you are arguing that the increased elasticity prevents spokes going
slack and thereby reducing fatigue. it's all in your book.

I presented the case for buttes spoke to be more elastic and
distribute loads over a greater number of spokes. You may have
interpreted that to your beliefs, but it isn't there. I do not
attribute fatigue failures to slackening.

yes you do - your statements are mutually contradictory.

Quoted message said:

Quoted message said:

Quoted message said:

>> It fails because there are high stress points at that place and
>> that spokes that don't break must have lower stress. The lower
>> stress is achieved by stress relief and that this is possible by
>> mechanical means has also been explained in great detail.

Quoted message said:

Quoted message said:

> I do believe it's possible. But so are alien abductions, and I
> don't think they happen.

Quoted message said:

Quoted message said:

Why don't you believe that is possible?

Quoted message said:

Quoted message said:

For example, stretch a spoke with a bend at midspan to yield (as is
done when drawing the wire) and when I performed tensile tests on
spokes, and release it. The spoke will be as straight as
imaginable and its entire cross section will be uniformly at zero
stress even though it originally had a bend in it with residual
stress, as was explained ignoring threads and elbow in order to
isolate the process.

Quoted message said:

it straightens because it yields! duh.

Quoted message said:

Quoted message said:

Yielding the material will bring it to uniform stress throughout
and relaxing to zero will leave a uniformly stressed wire.

Quoted message said:

no. stresses resolve hydrostatically. that's why ductile tensile
fracture surfaces have the "cup and cone" feature.

http://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/exper/bailey/www/fig6.jpg

Quoted message said:

jeepers jobst, that's a *huge* misconception.

Maybe you can explain what your reference is demonstrating. This is
apparently not a fatigue failure and not on a spoke. I don't see what
this has to do with the sentence above the reply.

you said that stress is uniform due to loading. it is not. cup and
cone fracture is evidence of that. again, i can send you data on the
theory if you don't have access to it. basically, tensile stress in one
axis resolves itself into compression in the other two axes. this is
where poisson's ratio comes from. in addition, there are surface
effects, and it's also affected by overall size, hence the use of fine
fiber in composites.

Quoted message said:

Quoted message said:

no. see above. there's /way/ more to deformation than you're assuming
here.

Don't keep it a secret.

see above. you need to look it up.

Quoted message said:

Quoted message said:

Quoted message said:

with no tensile stress. If you slice this even finer, radially
there may be small residual radial stresses that do not materially
affect tensile loads.

Quoted message said:

residual stress has /nothing/ do do with load!!!

Fatigue failures have much to do with residual stress overlayed on
cyclic operational loads.

but you said "there may be small residual radial stresses that do not
materially affect tensile loads." you contradict yourself.

Quoted message said:

Looking out of the box makes it difficult
to see what's in the box, and residual stress along with working loads
are the problem.

but you're presuming that. examination of failures show that residual
stress, compressive residual stress no less in the case of an elbow
outer, makes no material impact on fatigue life. in addition, such
residual stress as there might be is minimal at the point where fatigue
initiates, and the points at which residual stress is the greatest,
/never/ see fatigue initiation!!!

Quoted message said:

Quoted message said:

Quoted message said:

The magnitude and orientation of these stresses are insignificant
for a wire.

Quoted message said:

rubbish - they're fundamental to deformation and failure of each
strand - the means by which rope breaks.

OH! That must be why spokes don't fail at midspan even though they
have been deformed. There aren't high enough stresses remaining in
the spoke, even in its reduced cross section to cause fatigue failure.

red herring. greatest residual stress is in the center of a spoke, not
the skin. yet fatigue always initiates at the skin. and besides,
"There aren't high enough stresses remaining in the spoke, even in its
reduced cross section to cause fatigue failure." contradicts all your
elbow residual stress presumptions.

Quoted message said:

Quoted message said:

Quoted message said:

If that weren't so we could have few cables or wires to carry
loads.

Quoted message said:

simplistic mistaken nonsense.

I don't see an explanation for your point of view.

jobst, cold worked wire has a very high dislocation density. by
definition, that means very high lattice stress. that in conjunction
with that high dislocation density can be ripe for fatigue. yet wires
not only carry loads, they do so successfully with limited [largely
predictable] fatigue.

Quoted message said:

Quoted message said:

Quoted message said:

>>> I don't see how we are expected to draw any other conclusion
>>> from this than that as far as we can tell residual stress is
>>> unlikely to be related to spoke failure.

Quoted message said:

Quoted message said:

>> That is what I find so inexplicable in this discussion. On the
>> one hand, detailed explanations seem to be too cryptic to
>> understand

Quoted message said:

Quoted message said:

> Certainly I don't understand some of your explanations, mainly
> point 4 above:

Quoted message said:

Quoted message said:

>> 4. That adding tension to the spoke guarantees that the stress at
>> the outside of the elbow remains at yield, that being the
>> highest load it can withstand.

Quoted message said:

Quoted message said:

> and what's wrong with the other explanations for spoke failure.

Quoted message said:

Quoted message said:

They lie as remote possibilities as causes of failures in these
spokes,

Quoted message said:

"remote possibilities"!!! if you knew about fatigue, you might
understand how stupid that statement is!

Thanks again.

again jobst, the main factors in fatigue are design, surface, material
and lastly residual stress. since the first 3 are easily observed and
the last is unproven, you can't just make presumptive statements.

Quoted message said:

Quoted message said:

Quoted message said:

and I take DT as the prime example, they having one of the best
wire suppliers and have been working on reliability as long as any.
Their wire is not full of random flaws and other chemical anomalies
cited as spoke failure causes under the guise of metallurgical
jargon.

Quoted message said:

that's rich!

Quoted message said:

Quoted message said:

If that were so, there would be systematic failure of their spokes
and not only at the elbow and threads.

Quoted message said:

rubbish. spoke fatigue initiates at the point of maximum stress.
maximum stress is caused either by a riser or by an applied load.
risers have many forms. applied is caused by mechanical
configuration, in this case by having load applied off-axis via an
offset shank and elbow.

So why are these failures concentrated at points that have stress up
to yield as at outside of elbows and at the root of threads.

they're not close to yield. if they were, fatigue would be absolute and
spokes would fail well within 10^3 cycles - clearly not the case. look
at any s-n graph.

Quoted message said:

One
might deduce that the manufacturer knowingly concentrates these
anomalies at those points to support the theory of no residual stress.

eh? how are they going to do that? as long as wheel builders keep
using elbowed spokes, not straight pull, this problem is going to
continue to exist.

Quoted message said:

Quoted message said:

Quoted message said:

In contrast, DT spokes (and other good spokes) still fail on poorly
built wheels.

Quoted message said:

including your very own "stress relieved" wheels.

Thanks again. You know that is untrue but toss it out just the same.

jobst, your spokes have fatigued and broken. you've said so.
unsurprising since spokes are made of stainless tell with no endurance
limit and in a configuration that subjects them to constant bending.

Quoted message said:

Quoted message said:

Quoted message said:

Don't lose sight of Richard Feynman's classic comment: "If you
can't explain it in plain English, you don't understand it
yourself."

Quoted message said:

what relevance is that to someone that is not only trying to tell us
a good deal more than they actually understand, but won't bother to
do any homework. no amount of "plain english" can cover that kind
of stupidity.

Quoted message said:

Quoted message said:

What is poor about these wheels???? Their build! Failure to
improve spoke line and stress relieve.

Quoted message said:

bending spokes can increase residual stress, increase surface
defects, increase dislocation density, and if performed prematurely,
lead to spoke alignment issues since the spoke is being forced to
conform with a hub not yet yielded to its final shape. maybe that's
why manufacturers specifically say not to do it. but how would they
know - they only do research - such a waste when they could make
under-informed assumptions and save themselves so much money and
effort. incidentally, when are you going to perform your residual
stress testing?

When are you going to explain what occurs in wheel building that will
build more durable wheels and prevent spoke failures? You seem to
believe that it is solely my duty to test every hypothesis that can be
presented on the subject here on wreck.bike.

i repeatedly have. all that's happening with "stress relief" is that
the spokes are seating in to the hub. this allows them to remain close
to original tension, and thus minimize excessive bending that individual
slackness causes. minimized bending means minimized fatigue. real
simple. as for testing, if you want to propose fatigue elimination
theories that contradict a century of materials research, you need data
to support it. presence of residual stress can be tested for literally
cents. if you want to show you can eliminate fatigue by mechanical
means, you need test structured testing and structured results to prove
it. that'll cost you more, but since you're the guy out of step, the
onus is on you to make that investment. consider it "reinvestment" of
book sales proceeds.

jim beam said:

Gary Young said:

On Sun, 31 Dec 2006 16:55:22 -0800, jim beam wrote: <snip>

Quoted message said:

bending spokes can increase residual stress, increase surface defects,
increase dislocation density, and if performed prematurely, lead to
spoke alignment issues since the spoke is being forced to conform with
a hub not yet yielded to its final shape. maybe that's why
manufacturers specifically say not to do it.

As you should know, since it's been pointed out to you before,
Bontrager recommends correcting the spoke lines on its wheels:

http://tinyurl.com/7fkbv (pdf) -- see page 7.

Gerd Schrander, whose book (the German edition) is sold by DT and
touted on its website, recommends correcting the spoke line:

"Another small job simply involves bending the spokes at the nipple
ends - the misalignment of spoke and nipple depends on the number of
spokes and the spoking method used. Hold crossed pairs of spokes and
squeeze them together. The spokes are made of flexible wire and so
bending them in this way does no harm whatsoever."

Page 85 of the English edition.

Eric Hjertberg, one of the founders of Wheelsmith, recommends
correcting the spoke line:

"Now that each spoke is adjusted to the same length as its neighbors,
it's time to bend the spokes near their elbow so they fully conform to
their direction. Do it by inserting a stout screwdriver shaft between
two spokes, just under one of the crosses. Once in this triangle, lever
the screwdriver so the handle end rests against the outside spoke and
the blade end presses against the inside spoke. A gentle push will bend
them into conformity. Go around the wheel "setting in" pairs. This
procedure stabilizes the wheel by doing immediately what normally
occurs during miles of riding. The life of each spoke is enhanced
because each elbow bends less after it conforms to its path. Otherwise,
it constantly tries to recover its original shape during riding and
fatigues more quickly."

www.crazyrides.com/en/mastermechanic/part2.htm

The only evidence I see that manufacturers frown on correcting the
spoke line is a Sapim FAQ that's riddled with errors.

Do you have some other evidence?

let me repeat:
"bending spokes can increase residual stress, increase surface defects,
increase dislocation density, and if performed prematurely, lead to
spoke alignment issues since the spoke is being forced to conform with a
hub not yet yielded to its final shape."

any questions?

Yeah, when are you going to stop dodging questions? Do you have any other
evidence that manufacturers frown on correcting the spoke line? (Even if
that hadn't been my question, simply reiterating your assertions doesn't
count as evidence.)

Quoted message said:

regarding your citations, none bar wheelsmith are spoke manufacturers -
they simply assemble wheels from components they buy in.

DT isn't a spoke manufacturer? DT publishes, or at least distributes,
Schraner's book, touts it in its online materials (see, for instance, the
instructions to the DT tensiometer), and Schraner has taught at
DT-sponsored wheelbuilding seminars (at which participants can receive a
diploma as a "DT Certified Wheelbuilder" -- see page 101 of his book).

As for Bontrager being a mere assembler of wheels, presumably it also has
to service its own wheels and thus would have some interest in learning
what leads to failure. Besides, I don't think you can get away with
limiting things to spoke manufacturers. Your whole theory that spoke lines
don't need to be corrected depends on co-ordination between manufacturers
of spokes, rims, and hubs. In order to achieve the degree of perfection
that you claim, they would all have to understand the issues or at least
be in communication with each other. To say that only spoke makers know
what they're doing tends to cut against your argument.

it's also

Quoted message said:

worth noting that bontrager have been savaged by jobst over the years,
schraner has been excoriated for saying that hubs hang from upper
spokes, and hjertberg is a buddy of jobst.

So what?

First you argue that manufacturers know what they're doing (or at least,
know better than Jobst). Then I present examples in which they disagree
with you. And now you're arguing that they don't know what they're doing
or that they're just aping what Jobst says? Do you see a problem here?

I suspect that some of them are very wrong, just as I've argued that
Sapim's FAQ is filled with errors. But I'm not the one who argues that
manufacturers know what's best.

i don't know wheelsmith's

Quoted message said:

position on this, but since they tend to be a little coy with details
such as how exactly their spokes are made,

The coyness is in your head. Wheelsmith says that the center sections of
its spokes are forged and you've presented no credible evidence otherwise.

By the way, here's another indication that Wheelsmith doesn't frown on
correcting spoke lines:

"The Wheelsmith elbow radius is large so the spoke will require a minimum
of bending to conform to the hub."

www.wheelsmith.com/index_files/spoketech.htm

Quoted message said:

they may be choosing to swim
with the tide rather than fight against entrenched jobstian myopia.

Swimming against the tide? Entrenched Jobstian myopia? I thought you said
that all the other spoke makers disagree with Jobst? If so, in what way
would Wheelsmith be swimming against the tide by disagreeing with him?

Quoted message said:

there are countless other cases of people mindlessly repeating jobstian
drivel. example: increasing spoke tension increases wheel strength,
rims crack because of anodizing, fatigue can be eliminated by "stress
relief", etc. but all i see that repetition proving is the willingness
of people to believe and take on faith rather than question and seek
fact.

Yada, yada, yada. Completely beside the point. Do manufacturers repudiate
Jobst's views or not?

Quoted message said:

did /you/ notice any of jobst's errors in his book? if not, then you're
likely to repeat them too.

Given the fact that I'm not an engineer, I'm at somewhat of a disadvantage
when wading through the issues here on rbt. It's rare that I have the
in-depth knowledge to judge things for myself in real time (though I do
think I've acquired more depth over the years). By necessity, I'm forced
to rely on judgments of credibility.

In fact, since you've obviously had more engineering training than I, I
wouldn't ordinarily be sparring with you. What gives me the courage to do
so are your errors in simple logic, self-contradictions, unwillingness to
admit error, sock-puppetry, and refusal to state the training or
experience that gives you warrant to lecture us.

That's why I don't put much credibility in what you say.

On 31 Dec 2006 20:02:39 -0800, "Ron Ruff" <[email hidden]>

Quoted message said:

Makes me wonder what danger there would be in *over* bending the elbow
to conform to the hub. Seems like this would be preferable...

The Eric Hjertberg method of bending the spokes around with a screw
driver *inside* the crossing would certainly achieve this.

I just rebuilt a wheel, resuing 1.8/1.55mm spokes that previously had
DT washers under the heads. Some of the washers cracked in two when I
moved the spokes, so I decided to get rid of them... only now the
spokes are not shaped to fit the hub so well. I bent the spokes inside
the cross (2x 32 hole) using a srew driver, *after* the wheel was fully
tensioned, so that now the J resembles the the hook that goes on the
end of chains... ie the spoke wraps around the flange a bit, and the
center of the spoke line for both inside and outside spokes heads to
the center of the hub flange. Comments?

Dear Ron,

Just to clarify . . .

Is this screwdriver technique like Sheldon's twisting on the outside
of the spoke crossing with a smooth pedal arm, only with the much
smaller lever of a screwdriver shaft on the inside of the crossing?

rim rim
x x x x
x x x x
x S x x x
x x x x
x x
x x xEx
x x x x
hub hub

S = where R = where
Sheldon Eric
twists twists
with a with a
big pedal screwdriver
arm

Here's Sheldon's description with a picture:

http://www.sheldonbrown.com/wheelbuild.html#seating

Cheers,

Carl Fogel

Gary Young said:

jim beam said:

Gary Young said:

On Sun, 31 Dec 2006 16:55:22 -0800, jim beam wrote: <snip>

> bending spokes can increase residual stress, increase surface defects,
> increase dislocation density, and if performed prematurely, lead to
> spoke alignment issues since the spoke is being forced to conform with
> a hub not yet yielded to its final shape. maybe that's why
> manufacturers specifically say not to do it.
As you should know, since it's been pointed out to you before,
Bontrager recommends correcting the spoke lines on its wheels:

http://tinyurl.com/7fkbv (pdf) -- see page 7.

Gerd Schrander, whose book (the German edition) is sold by DT and
touted on its website, recommends correcting the spoke line:

"Another small job simply involves bending the spokes at the nipple
ends - the misalignment of spoke and nipple depends on the number of
spokes and the spoking method used. Hold crossed pairs of spokes and
squeeze them together. The spokes are made of flexible wire and so
bending them in this way does no harm whatsoever."

Page 85 of the English edition.

Eric Hjertberg, one of the founders of Wheelsmith, recommends
correcting the spoke line:

"Now that each spoke is adjusted to the same length as its neighbors,
it's time to bend the spokes near their elbow so they fully conform to
their direction. Do it by inserting a stout screwdriver shaft between
two spokes, just under one of the crosses. Once in this triangle, lever
the screwdriver so the handle end rests against the outside spoke and
the blade end presses against the inside spoke. A gentle push will bend
them into conformity. Go around the wheel "setting in" pairs. This
procedure stabilizes the wheel by doing immediately what normally
occurs during miles of riding. The life of each spoke is enhanced
because each elbow bends less after it conforms to its path. Otherwise,
it constantly tries to recover its original shape during riding and
fatigues more quickly."

www.crazyrides.com/en/mastermechanic/part2.htm

The only evidence I see that manufacturers frown on correcting the
spoke line is a Sapim FAQ that's riddled with errors.

Do you have some other evidence?

let me repeat:
"bending spokes can increase residual stress, increase surface defects,
increase dislocation density, and if performed prematurely, lead to
spoke alignment issues since the spoke is being forced to conform with a
hub not yet yielded to its final shape."

any questions?

Yeah, when are you going to stop dodging questions?

eh? it's not a dodge! i've repeatedly cited the primary factors in
spoke fatigue, and these are configuration, surface finish material, and
latterly, residual stress. the above explains part of the reasoning why
- bending can increase residual stress and increase surface damage,
higher dislocation density can help initiate fatigue, and premature
bending can affect configuration. if that's not being clear, ask for
clarification. but don't say it's dodging the question because it's not.

Quoted message said:

Do you have any other
evidence that manufacturers frown on correcting the spoke line? (Even if
that hadn't been my question, simply reiterating your assertions doesn't
count as evidence.)

sapim are most specific about it. sapim are also the only manufacturer
that have the minerals to publish fatigue data.

Quoted message said:

Quoted message said:

regarding your citations, none bar wheelsmith are spoke manufacturers -
they simply assemble wheels from components they buy in.

DT isn't a spoke manufacturer? DT publishes, or at least distributes,
Schraner's book, touts it in its online materials (see, for instance, the
instructions to the DT tensiometer), and Schraner has taught at
DT-sponsored wheelbuilding seminars (at which participants can receive a
diploma as a "DT Certified Wheelbuilder" -- see page 101 of his book).

but gary, with all due respect to schraner, he's not an engineer. he's
an artisan of the greatest sincerity, but that doesn't mean he knows
what's going on.

Quoted message said:

As for Bontrager being a mere assembler of wheels, presumably it also has
to service its own wheels and thus would have some interest in learning
what leads to failure.

presumably, but they're still using elbowed spokes [last time i
checked]. use of straight pull would reduce fatigue by an order of
magnitude, but they haven't done it. why? the engineering reasons to
do so are compelling. one may therefore question their "interest" in
this subject.

Quoted message said:

Besides, I don't think you can get away with
limiting things to spoke manufacturers. Your whole theory that spoke lines
don't need to be corrected depends on co-ordination between manufacturers
of spokes, rims, and hubs.

no it doesn't! i don't think you should bend spokes. i've cited the
reasons why. i think straight pull spokes have a serious fatigue
advantage over elbowed. i've cited the reasons why. the information is
out there. if manufacturers don't want to execute, that's their call.

Quoted message said:

In order to achieve the degree of perfection
that you claim, they would all have to understand the issues or at least
be in communication with each other. To say that only spoke makers know
what they're doing tends to cut against your argument.

see above. [some] spoke makers /do/ seem to know what they're doing.
but they'd be damned fools to suddenly stop selling elbowed spokes for
instance, even though it makes a lot more sense to do so.

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it's also

Quoted message said:

worth noting that bontrager have been savaged by jobst over the years,
schraner has been excoriated for saying that hubs hang from upper
spokes, and hjertberg is a buddy of jobst.

So what?

the "so what?" is that some people simply kow-tow rather than stand up
for themselves. tom ritchey used to contribute to this group, but got
so badly mauled, he left in disgust. a sad loss. but jobst would
rather have that than concede he'd ever made mistakes, let alone bother
to correct them. the peanut gallery joining in the spectacle and
throwing stones is simply perverse.

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First you argue that manufacturers know what they're doing (or at least,
know better than Jobst).

some spoke manufacturers, yes.

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Then I present examples in which they disagree
with you.

i don't believe wheelsmith "cold forge" the butting on their spokes, no.
from what i can observe, i believe they grind and polish, just like
ashai, the people from whom they bought their manufacturing equipment, do.

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And now you're arguing that they don't know what they're doing
or that they're just aping what Jobst says? Do you see a problem here?

yes, i see a problem, but it's apparently different from the one you're
hinting at!

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I suspect that some of them are very wrong, just as I've argued that
Sapim's FAQ is filled with errors. But I'm not the one who argues that
manufacturers know what's best.

then discuss the errors! you can even email sapim if you want to. i
have in the past and they've been most pleasant.

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i don't know wheelsmith's

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position on this, but since they tend to be a little coy with details
such as how exactly their spokes are made,

The coyness is in your head. Wheelsmith says that the center sections of
its spokes are forged and you've presented no credible evidence otherwise.

with respect gary, i have a little experience in observing manufacturing
technique. these spokes /look/ like they're ground and polished. i
can't /prove/ that unless i have one under the metallurgical microscope,
but that observation is consistent with what is known of their
manufacturing mentors, ashai.

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By the way, here's another indication that Wheelsmith doesn't frown on
correcting spoke lines:

"The Wheelsmith elbow radius is large so the spoke will require a minimum
of bending to conform to the hub."

www.wheelsmith.com/index_files/spoketech.htm

great.

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they may be choosing to swim
with the tide rather than fight against entrenched jobstian myopia.

Swimming against the tide? Entrenched Jobstian myopia? I thought you said
that all the other spoke makers disagree with Jobst?

no, i said they're probably choosing to swim with the tide and not argue.

Quoted message said:

If so, in what way
would Wheelsmith be swimming against the tide by disagreeing with him?

how are they disagreeing? the above contradicts your statement.

Quoted message said:

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there are countless other cases of people mindlessly repeating jobstian
drivel. example: increasing spoke tension increases wheel strength,
rims crack because of anodizing, fatigue can be eliminated by "stress
relief", etc. but all i see that repetition proving is the willingness
of people to believe and take on faith rather than question and seek
fact.

Yada, yada, yada. Completely beside the point. Do manufacturers repudiate
Jobst's views or not?

that precisely /is/ the point. jobstian myths are rampant in the
english speaking industry simply because he's been such a shameless
bully and self-promotionist. but it doesn't mean he's right or that he
knows what he's doing. the above are examples often repeated, even
though they're incorrect. some manufacturers /do/ contradict by action,
but why would they waste time arguing with him on a group like this?

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did /you/ notice any of jobst's errors in his book? if not, then you're
likely to repeat them too.

Given the fact that I'm not an engineer, I'm at somewhat of a disadvantage
when wading through the issues here on rbt. It's rare that I have the
in-depth knowledge to judge things for myself in real time (though I do
think I've acquired more depth over the years). By necessity, I'm forced
to rely on judgments of credibility.

based on what? if you can't tell fact from fiction, your basing your
judgment on non-factual criteria, in this case, the guy that tells you
he's right, regardless of whether he actually is. kinda scary actually.

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In fact, since you've obviously had more engineering training than I, I
wouldn't ordinarily be sparring with you. What gives me the courage to do
so are your errors in simple logic, self-contradictions, unwillingness to
admit error, sock-puppetry, and refusal to state the training or
experience that gives you warrant to lecture us.

That's why I don't put much credibility in what you say.

you don't have to believe /anything/ i say. i'm not forcing you. but
i'm not selling you either and i have no vested interest in creating an
illusion of competence to support any meager living. if you want to
check facts, i'll give you references and you can go to the library and
check for yourself. alternatively, you can invest a little time and
energy like carl fogel and do your own research.