Spoke tension meter

[jim beam]

Luns Tee wrote:
> In article <[email protected]>,
> Sheldon Brown <[email protected]> wrote:
>
>>Back in the '70s and early '80s, nipples pulling through the rim were
>>exceedingly uncommon, and the usual cause of spoke breakage was
>>insufficient spoke tension.
>
>
> While we're at it.. please explain how insufficient spoke
> tension causes spoke breakage. Inadequate tension produces an inferior
> wheel, certainly, but the failure of low spoke tension is that spokes
> go slack under load, allowing spoke nipples to rattle loose and the
> wheel to then go out of true.

slack spokes are not intrinsically less strong, and as you point out,
their biggest problem is tendency to loosen, but there /is/ a
reliability problem with them. it's caused by exaggerated bending as a
result of their interaction with their crossing partner. spokes
typically fatigue at the elbow as a result of bending - they are not
axially loaded. if the motion they experience is exaggerated because of
excessive [slack] spoke movement, and even further exaggerated by their
[still taught] crossing partner creating even more lateral movement, the
[bending] strain they experience at the elbow increases and their
fatigue life correspondingly decreases.

> Spoke breakage is not part of this, even
> if it was more common at the time. But so were bell bottom pants.
>
> Bell bottom pants cause spoke breakage!
>
> -Luns
>

 

[Luns Tee]

In article <[email protected]>,
jim beam <[email protected]> wrote:
>slack spokes are not intrinsically less strong, and as you point out,
>their biggest problem is tendency to loosen, but there /is/ a
>reliability problem with them. it's caused by exaggerated bending as a
>result of their interaction with their crossing partner. spokes
>typically fatigue at the elbow as a result of bending - they are not
>axially loaded. if the motion they experience is exaggerated because of
>excessive [slack] spoke movement, and even further exaggerated by their
>[still taught] crossing partner creating even more lateral movement, the
>[bending] strain they experience at the elbow increases and their
>fatigue life correspondingly decreases.

If there were any truth to this, then left side spokes on rear
wheels would universally fatigue more than right side spokes do. My
experience with fatigued spokes has been consistently the opposite. My
experience with fatigued spokes also ended with stress releiving the
surviving spokes on the wheels that had failures, something which
should have made no effect according to your movement theory.

-Luns

 

[Joe Riel]

jim beam writes:

> the offset for the drive side of a campy hub is only 18mm. even if my
> top tube is 3x as high as my hub [which it's not], that's still only
> 54mm offset from the vertical. check how that is on your bike - it's
> not a lot of lean.

Agreed. However, the bike doesn't lean much, even while standing
during a climb. Try it. Look at the pictures that were linked
to in this thread.

On reflection, though I wouldn't be surprised if the bottom spoke does
move past the perpendicular. But does it enough to cause a
significant tension increase? I suspect not. I leaned my bike (to
the right) against a wall, at an angle that I might achieve during
out-of-the-saddle climbing. The bottom spoke was past vertical. I
then stood on the left side of the bottom bracket, facing backwards,
reached down and plucked the bottom spoke. I could detect no change
in tone upon removing my weight. This isn't a perfect test, but it
does indicate that an increase in tension is not going to be large.
If I leaned the bike enough I could detect a tension (pitch) increase,
however, the lean was past what I consider realistic.

Joe

 

[Joe Riel]

jim beam <[email protected]> writes:

>> The simple model of the wheel used above is not, alas, complete.
>> As pointed out in "Bicycling Science" (3rd ed.) more spokes are
>> affected by a lateral load than by a radial load. Maybe the spokes
>> around the bottom spoke(s) see an increase in tension.
>
> sure, but there's not much "maybe" about it - the ping test reveals all!

See my reply to your other reply. I detected no increase in tension
in the lower right side spokes with the bike leaned at a reasonable
angle (bottom left-side spoke past vertical). Also, pay close attention,
while climing, how much the frame really leans. It isn't as much
as you might think.

To have some numbers to throw around, I (crudely) measured that, with
the bike leaned and tone not changing, the top tube moved six inches
horizontally (my top tube is 31 inches from the ground). The total
side to side movement would then be 12 inches, which is quite a bit.

Joe

 

[[email protected]]

On Thu, 16 Jun 2005 05:01:18 GMT, Joe Riel
<[email protected]> wrote:

>jim beam writes:
>
>> the offset for the drive side of a campy hub is only 18mm. even if my
>> top tube is 3x as high as my hub [which it's not], that's still only
>> 54mm offset from the vertical. check how that is on your bike - it's
>> not a lot of lean.
>
>Agreed. However, the bike doesn't lean much, even while standing
>during a climb. Try it. Look at the pictures that were linked
>to in this thread.
>
>On reflection, though I wouldn't be surprised if the bottom spoke does
>move past the perpendicular. But does it enough to cause a
>significant tension increase? I suspect not. I leaned my bike (to
>the right) against a wall, at an angle that I might achieve during
>out-of-the-saddle climbing. The bottom spoke was past vertical. I
>then stood on the left side of the bottom bracket, facing backwards,
>reached down and plucked the bottom spoke. I could detect no change
>in tone upon removing my weight. This isn't a perfect test, but it
>does indicate that an increase in tension is not going to be large.
>If I leaned the bike enough I could detect a tension (pitch) increase,
>however, the lean was past what I consider realistic.
>
>Joe

Dear Joe,

What pictures?

Do they show a sequence of side-to-side sway?

I've been wondering about how much actual side-tilt there is
and whether I've been fooled by the shoulder-drop when the
rider sort of twists and curls down (rather than to the
side) toward the foot at the bottom of the stroke.

Elsewhere, Mike Jacoubowsky and RonSonic were trying to
explain something about how differently ordinary and expert
riders move on the bike when standing, so this might be what
they were trying to get at:

http://groups.google.co.uk/group/re...183b8dcb1a0/74b186b953f2aba9#74b186b953f2aba9

(Boy, that new Google is a beast when you want a link to the
right part of the tree!)

Hopefully,

Carl Fogel

 

[[email protected]]

Marvin Meredith writes:

>>>>> On the road, however, the rear wheel is not displaced by
>>>>> laterally loading the rim at the brake, which minimizes the
>>>>> required force. The forces involved may require substantial
>>>>> changes in spoke tension. That has to be shown.

>>>> I agree and that is easily done. I suggest that you stand on the
>>>> pedals and lean the bicycle to the side, as one does when
>>>> pedaling on a hill, and do a tone test. You'll find that there
>>>> is no significant change in tension of the upper spokes (the ones
>>>> near the brake pad).

> But as any good student of the Bicycle Wheel will know, tension
> changes from ground contact only affect the bottom few spokes in any
> significant manner. Surely it's those we ought to be measuring?

I think I said that and you quote that below at "Oops".

>>>> This is a false visualization of spoke stresses similar to "the
>>>> wheel hangs from the top spokes" scenario. The change lies in
>>>> the amount of slackening of left and right spokes at the ground
>>>> contact zone.

>>> I'm not convinced here. I'll accept (as in the Bicycle Wheel)
>>> that spokes lose tension from a radial load, so the spokes at the
>>> bottom of a wheel are the lightest loaded. I'll also accept that
>>> lateral loading has no overall effect, only to change the balance
>>> between left and right side spokes. This obviously means one side
>>> increases in tension relative to the other.

>> Oops! No, that is not the case. One side loses more tension than
>> the other and only at the ground contact zone. You needn't take
>> this on faith. It is easy to test as has been explained.

> Yes, I just tested it and got exactly the result I expected - higher
> tension in the spokes nearest the ground. Perhaps we're measuring
> different things, so I'll describe this in painstaking detail.

How far did you lean the bicycle? No doubt as the lean angle get
large, larger than when riding, it starts becoming more a side load on
the wheel similar to pushing the rim sideways at the brake bridge.

> I sit on a bike, holding a wall for support but otherwise as upright
> as I can get. My lovely assistant pings all the spokes in the front
> wheel, and they conform to what the Bicycle Wheel suggests - drop of
> tension in about four spokes around the ground contact, all others
> even.

> I lean the bike to the left whilst leaning myself right to load the
> wheel axially, and she repeats the experiment. All the spokes have
> even tension except the load-affected ones. Of those, the righthand
> spokes have lower tension than anything so far, and the lefthand
> spokes have higher tension than they ever did. For those of you who
> skipped to the interesting bit: leaning the bike raised the spoke
> tension.

> My assistant leaves with a shrug of her shoulders and "see, I could
> have told you that".

> If I'm measuring the wrong thing, please do tell me what I'm doing
> wrong, but otherwise I think a rethink is in order.

Again, how far did you lean the bicycle? When I perform this test it
responds as described above. The high side loses more tension than
the low side, but they both lose tension. Other spokes of the wheel
do not change audibly. In normal bicycling, riders climb hills
standing by leaning enough to make the high side spokes stand vertical
to the road. If you doubt this, I suggest a road test while sighting
down through the front hub.

I don't know how high the spoke tone went but I'll bet it is lower than
the tone of the rear spokes in the front wheel

[email protected]

 

[[email protected]]

On Thu, 16 Jun 2005 05:55:24 GMT,
[email protected] wrote:

[snip]

>How far did you lean the bicycle? No doubt as the lean angle gets
>large, larger than when riding, it starts becoming more a side load on
>the wheel similar to pushing the rim sideways at the brake bridge.

[snip]

Dear Jobst,

What's a large lean-angle in degrees when riding?

And is it different for climbing a steep slope versus
sprinting on the level for the finish line?

I'm not arguing, just hoping that someone is going to find a
link to some article that explains how much a bicycle
actually tilts from side to side.

I understand that the tilt may differ for amateurs and pros.
(Or maybe it doesn't--that's one of the things that I'm
wondering about.)

I realize that tilt may vary widely according to purely
individual style. (That's another question--maybe we're not
nearly as unique as we like to think, or maybe some of us
wobble far more entertainingly than others.)

Joe Riel mentions some pictures, but didn't give any links.
He also has made some efforts to measure how far his top
tube sways, but all I can do is applaud his efforts and
wonder if he's normal, extra-steady, or Bronco Billy.

(You and I can appreciate how easily our own habits distort
our perceptions--you can't help thinking that mashing up
Alpine passes in high gears on a six-speed is normal, while
I assume that everyone would be happy riding along a river
with a 7-speed 53x11 at a glacial cadence.)

Carl Fogel

 

[[email protected]]

Sheldon Brown writes:

>> Besides, spoke stress is not what the wheelbuilder wants to know,
>> since correct spoke tension is prescribed for a specific rim,
>> rather than stress in its spokes.

> That's true with modern lightweight rims and high quality spokes.
> It is not universally true, however, and at the time John was doing
> the research that led to this article lower quality spokes were the
> norm, as were heavier, stronger rims.

> Back in the '70s and early '80s, nipples pulling through the rim
> were exceedingly uncommon, and the usual cause of spoke breakage was
> insufficient spoke tension. Tensiometers were not generally
> available, and John provided a useful service by offering a way an
> inexperienced wheelbuilder could get some idea of correct spoke
> tension.

I am not aware of spoke failure caused by insufficient tension. How
does that occur and for what mechanical reason?

Not only is my recollection of failures different but I have a stack
of more than 20 worn out MA-2 rims, none of which have cracks around
spoke eyelets. These were wheels that I built to the maximum safe
tension that I arrived upon when I discovered that some people built
wheels with too high spoke tension and whose wheels warped under hard
braking, the only load that uniformly increases spoke tension in any
part of the wheel.

Cracked rims, in contrast, appeared suddenly with the arrival of hard
and thickly anodized rims, the most obvious one being the MA-40 that
is identical to the non-cracking MA-2 except for the anodizing. Other
brands that offered hard anodized rims also had cracking problems, so
much so that whole rims separated along the inner chamber, having
thinner walls than the braking surface. That caused the tire to
remain on the thicker walled outer portion and being without sockets,
the inner portion was left attached to the spokes.

We have not made progress in that department. Few rims today have
sockets that distribute spoke loads to both walls and some not even
eyelets, meanwhile anodizing is still used although more sparingly.

[email protected]

 

[Marvin]

[email protected] wrote:
> Marvin Meredith writes:
>
> >>>>> On the road, however, the rear wheel is not displaced by
> >>>>> laterally loading the rim at the brake, which minimizes the
> >>>>> required force. The forces involved may require substantial
> >>>>> changes in spoke tension. That has to be shown.
>
> >>>> I agree and that is easily done. I suggest that you stand on the
> >>>> pedals and lean the bicycle to the side, as one does when
> >>>> pedaling on a hill, and do a tone test. You'll find that there
> >>>> is no significant change in tension of the upper spokes (the ones
> >>>> near the brake pad).
>
> > But as any good student of the Bicycle Wheel will know, tension
> > changes from ground contact only affect the bottom few spokes in any
> > significant manner. Surely it's those we ought to be measuring?
>
> I think I said that and you quote that below at "Oops".

Yes, we should measure the lower spokes, which I was doing anyway. You
said ten lines above there's no change in tension of the *upper*
spokes. Was this a completely unrelated fact, or were you trying to
confuse the issue?

> >>>> This is a false visualization of spoke stresses similar to "the
> >>>> wheel hangs from the top spokes" scenario. The change lies in
> >>>> the amount of slackening of left and right spokes at the ground
> >>>> contact zone.
>
> >>> I'm not convinced here. I'll accept (as in the Bicycle Wheel)
> >>> that spokes lose tension from a radial load, so the spokes at the
> >>> bottom of a wheel are the lightest loaded. I'll also accept that
> >>> lateral loading has no overall effect, only to change the balance
> >>> between left and right side spokes. This obviously means one side
> >>> increases in tension relative to the other.
>
> >> Oops! No, that is not the case. One side loses more tension than
> >> the other and only at the ground contact zone. You needn't take
> >> this on faith. It is easy to test as has been explained.
>
> > Yes, I just tested it and got exactly the result I expected - higher
> > tension in the spokes nearest the ground. Perhaps we're measuring
> > different things, so I'll describe this in painstaking detail.
>
> How far did you lean the bicycle? No doubt as the lean angle get
> large, larger than when riding, it starts becoming more a side load on
> the wheel similar to pushing the rim sideways at the brake bridge.

At the risk of sounding like jim beam, first you were loudly asserting
that there was *no* change in tension due to lateral loads, which we
now know isn't the case. Now it's lateral loads encountered during
"normal" riding. When I tell you my "normal" riding style involves a
fair amount of bike sway, especially during sprinting, doubtless you'll
further "clarify" your position.

In point of fact, the above test was done leaning the bike as far as I
"normally" would, although propping up against a wall is never the most
accurate gauge of such things. I'll try sighting through the front hub
when I go to work (which should have been five minutes ago).

> > I sit on a bike, holding a wall for support but otherwise as upright
> > as I can get. My lovely assistant pings all the spokes in the front
> > wheel, and they conform to what the Bicycle Wheel suggests - drop of
> > tension in about four spokes around the ground contact, all others
> > even.
>
> > I lean the bike to the left whilst leaning myself right to load the
> > wheel axially, and she repeats the experiment. All the spokes have
> > even tension except the load-affected ones. Of those, the righthand
> > spokes have lower tension than anything so far, and the lefthand
> > spokes have higher tension than they ever did. For those of you who
> > skipped to the interesting bit: leaning the bike raised the spoke
> > tension.
>
> > My assistant leaves with a shrug of her shoulders and "see, I could
> > have told you that".
>
> > If I'm measuring the wrong thing, please do tell me what I'm doing
> > wrong, but otherwise I think a rethink is in order.
>
> Again, how far did you lean the bicycle? When I perform this test it
> responds as described above. The high side loses more tension than
> the low side, but they both lose tension. Other spokes of the wheel
> do not change audibly. In normal bicycling, riders climb hills
> standing by leaning enough to make the high side spokes stand vertical
> to the road. If you doubt this, I suggest a road test while sighting
> down through the front hub.
>
> I don't know how high the spoke tone went but I'll bet it is lower than
> the tone of the rear spokes in the front wheel

....the what spokes in what?

 

[[email protected]]

Marvin Meredith writes:

>>>>>>> On the road, however, the rear wheel is not displaced by
>>>>>>> laterally loading the rim at the brake, which minimizes the
>>>>>>> required force. The forces involved may require substantial
>>>>>>> changes in spoke tension. That has to be shown.

>>>>>> I agree and that is easily done. I suggest that you stand on
>>>>>> the pedals and lean the bicycle to the side, as one does when
>>>>>> pedaling on a hill, and do a tone test. You'll find that there
>>>>>> is no significant change in tension of the upper spokes (the
>>>>>> ones near the brake pad).

>>> But as any good student of the Bicycle Wheel will know, tension
>>> changes from ground contact only affect the bottom few spokes in
>>> any significant manner. Surely it's those we ought to be
>>> measuring?

>> I think I said that and you quote that below at "Oops".

> Yes, we should measure the lower spokes, which I was doing anyway.
> You said ten lines above there's no change in tension of the *upper*
> spokes. Was this a completely unrelated fact, or were you trying to
> confuse the issue?

No, because the suggestion was made that the upper spokes are the ones
that increase in tension. To prove that contention, the writer
suggested pushing the rim sideways manually until it touched the brake
pad. The point is that up there, even with off axis loading, no
significant (audible) increase in tension occurs. That's where this
thread began. The proponents of this tack have changed the approach
since that venue collapsed.

>>>>>> This is a false visualization of spoke stresses similar to "the
>>>>>> wheel hangs from the top spokes" scenario. The change lies in
>>>>>> the amount of slackening of left and right spokes at the ground
>>>>>> contact zone.

>>>>> I'm not convinced here. I'll accept (as in the Bicycle Wheel)
>>>>> that spokes lose tension from a radial load, so the spokes at
>>>>> the bottom of a wheel are the lightest loaded. I'll also accept
>>>>> that lateral loading has no overall effect, only to change the
>>>>> balance between left and right side spokes. This obviously
>>>>> means one side increases in tension relative to the other.

>>>> Oops! No, that is not the case. One side loses more tension
>>>> than the other and only at the ground contact zone. You needn't
>>>> take this on faith. It is easy to test as has been explained.

>>> Yes, I just tested it and got exactly the result I expected -
>>> higher tension in the spokes nearest the ground. Perhaps we're
>>> measuring different things, so I'll describe this in painstaking
>>> detail.

>> How far did you lean the bicycle? No doubt as the lean angle get
>> large, larger than when riding, it starts becoming more a side load
>> on the wheel similar to pushing the rim sideways at the brake
>> bridge.

> At the risk of sounding like jim beam, first you were loudly
> asserting that there was *no* change in tension due to lateral
> loads, which we now know isn't the case. Now it's lateral loads
> encountered during "normal" riding. When I tell you my "normal"
> riding style involves a fair amount of bike sway, especially during
> sprinting, doubtless you'll further "clarify" your position.

I WHAT! I said nothing of the kind. I said at the brake bridge there
was no change. Let's not change horses in the middle of the wheel.

> In point of fact, the above test was done leaning the bike as far as
> I "normally" would, although propping up against a wall is never the
> most accurate gauge of such things. I'll try sighting through the
> front hub when I go to work (which should have been five minutes
> ago).

>>> I sit on a bike, holding a wall for support but otherwise as
>>> upright as I can get. My lovely assistant pings all the spokes in
>>> the front wheel, and they conform to what the Bicycle Wheel
>>> suggests - drop of tension in about four spokes around the ground
>>> contact, all others even.

>>> I lean the bike to the left whilst leaning myself right to load
>>> the wheel axially, and she repeats the experiment. All the spokes
>>> have even tension except the load-affected ones. Of those, the
>>> righthand spokes have lower tension than anything so far, and the
>>> lefthand spokes have higher tension than they ever did. For those
>>> of you who skipped to the interesting bit: leaning the bike raised
>>> the spoke tension.

>>> My assistant leaves with a shrug of her shoulders and "see, I
>>> could have told you that".

>>> If I'm measuring the wrong thing, please do tell me what I'm doing
>>> wrong, but otherwise I think a rethink is in order.

>> Again, how far did you lean the bicycle? When I perform this test
>> it responds as described above. The high side loses more tension
>> than the low side, but they both lose tension. Other spokes of the
>> wheel do not change audibly. In normal bicycling, riders climb
>> hills standing by leaning enough to make the high side spokes stand
>> vertical to the road. If you doubt this, I suggest a road test
>> while sighting down through the front hub.

>> I don't know how high the spoke tone went but I'll bet it is lower than
>> the tone of the rear spokes in the front wheel

> ...the what spokes in what?

The spokes pointing rearward in the front wheel when braking. You can
see the effect of this in diagrams in "the Bicycle Wheel".

[email protected]

 

[jim beam]

[email protected] wrote:
> Marvin Meredith writes:
>
>
>>>>>>>>On the road, however, the rear wheel is not displaced by
>>>>>>>>laterally loading the rim at the brake, which minimizes the
>>>>>>>>required force. The forces involved may require substantial
>>>>>>>>changes in spoke tension. That has to be shown.
>
>
>>>>>>>I agree and that is easily done. I suggest that you stand on
>>>>>>>the pedals and lean the bicycle to the side, as one does when
>>>>>>>pedaling on a hill, and do a tone test. You'll find that there
>>>>>>>is no significant change in tension of the upper spokes (the
>>>>>>>ones near the brake pad).
>
>
>>>>But as any good student of the Bicycle Wheel will know, tension
>>>>changes from ground contact only affect the bottom few spokes in
>>>>any significant manner. Surely it's those we ought to be
>>>>measuring?
>
>
>>>I think I said that and you quote that below at "Oops".
>
>
>>Yes, we should measure the lower spokes, which I was doing anyway.
>>You said ten lines above there's no change in tension of the *upper*
>>spokes. Was this a completely unrelated fact, or were you trying to
>>confuse the issue?
>
>
> No, because the suggestion was made that the upper spokes are the ones
> that increase in tension. To prove that contention, the writer
> suggested pushing the rim sideways manually until it touched the brake
> pad.

wow, that's a shameless distortion.

> The point is that up there, even with off axis loading, no
> significant (audible) increase in tension occurs. That's where this
> thread began. The proponents of this tack have changed the approach
> since that venue collapsed.

eh?

>
>
>>>>>>>This is a false visualization of spoke stresses similar to "the
>>>>>>>wheel hangs from the top spokes" scenario. The change lies in
>>>>>>>the amount of slackening of left and right spokes at the ground
>>>>>>>contact zone.
>
>
>>>>>>I'm not convinced here. I'll accept (as in the Bicycle Wheel)
>>>>>>that spokes lose tension from a radial load, so the spokes at
>>>>>>the bottom of a wheel are the lightest loaded. I'll also accept
>>>>>>that lateral loading has no overall effect, only to change the
>>>>>>balance between left and right side spokes. This obviously
>>>>>>means one side increases in tension relative to the other.
>
>
>>>>>Oops! No, that is not the case. One side loses more tension
>>>>>than the other and only at the ground contact zone. You needn't
>>>>>take this on faith. It is easy to test as has been explained.
>
>
>>>>Yes, I just tested it and got exactly the result I expected -
>>>>higher tension in the spokes nearest the ground. Perhaps we're
>>>>measuring different things, so I'll describe this in painstaking
>>>>detail.
>
>
>>>How far did you lean the bicycle? No doubt as the lean angle get
>>>large, larger than when riding, it starts becoming more a side load
>>>on the wheel similar to pushing the rim sideways at the brake
>>>bridge.
>
>
>>At the risk of sounding like jim beam, first you were loudly
>>asserting that there was *no* change in tension due to lateral
>>loads, which we now know isn't the case. Now it's lateral loads
>>encountered during "normal" riding. When I tell you my "normal"
>>riding style involves a fair amount of bike sway, especially during
>>sprinting, doubtless you'll further "clarify" your position.
>
>
> I WHAT! I said nothing of the kind. I said at the brake bridge there
> was no change. Let's not change horses in the middle of the wheel.

jobst, even you admit that on climbing, rims can rub brake pads. *by
definition*, that means that the upper part of the wheel is experiencing
lateral load, resulting from a much larger lateral loading at the bottom
part of the wheel. yet you now go back and twist your words in
avoidance??? that's ridiculous.

>
>
>>In point of fact, the above test was done leaning the bike as far as
>>I "normally" would, although propping up against a wall is never the
>>most accurate gauge of such things. I'll try sighting through the
>>front hub when I go to work (which should have been five minutes
>>ago).
>
>
>>>>I sit on a bike, holding a wall for support but otherwise as
>>>>upright as I can get. My lovely assistant pings all the spokes in
>>>>the front wheel, and they conform to what the Bicycle Wheel
>>>>suggests - drop of tension in about four spokes around the ground
>>>>contact, all others even.
>
>
>>>>I lean the bike to the left whilst leaning myself right to load
>>>>the wheel axially, and she repeats the experiment. All the spokes
>>>>have even tension except the load-affected ones. Of those, the
>>>>righthand spokes have lower tension than anything so far, and the
>>>>lefthand spokes have higher tension than they ever did. For those
>>>>of you who skipped to the interesting bit: leaning the bike raised
>>>>the spoke tension.
>
>
>>>>My assistant leaves with a shrug of her shoulders and "see, I
>>>>could have told you that".
>
>
>>>>If I'm measuring the wrong thing, please do tell me what I'm doing
>>>>wrong, but otherwise I think a rethink is in order.
>
>
>>>Again, how far did you lean the bicycle? When I perform this test
>>>it responds as described above. The high side loses more tension
>>>than the low side, but they both lose tension. Other spokes of the
>>>wheel do not change audibly. In normal bicycling, riders climb
>>>hills standing by leaning enough to make the high side spokes stand
>>>vertical to the road. If you doubt this, I suggest a road test
>>>while sighting down through the front hub.
>
>
>>>I don't know how high the spoke tone went but I'll bet it is lower than
>>>the tone of the rear spokes in the front wheel
>
>
>>...the what spokes in what?
>
>
> The spokes pointing rearward in the front wheel when braking. You can
> see the effect of this in diagrams in "the Bicycle Wheel".
>
> [email protected]

 

[jim beam]

[email protected] wrote:
> Sheldon Brown writes:
>
>
>>>Besides, spoke stress is not what the wheelbuilder wants to know,
>>>since correct spoke tension is prescribed for a specific rim,
>>>rather than stress in its spokes.
>
>
>>That's true with modern lightweight rims and high quality spokes.
>>It is not universally true, however, and at the time John was doing
>>the research that led to this article lower quality spokes were the
>>norm, as were heavier, stronger rims.
>
>
>>Back in the '70s and early '80s, nipples pulling through the rim
>>were exceedingly uncommon, and the usual cause of spoke breakage was
>>insufficient spoke tension. Tensiometers were not generally
>>available, and John provided a useful service by offering a way an
>>inexperienced wheelbuilder could get some idea of correct spoke
>>tension.
>
>
> I am not aware of spoke failure caused by insufficient tension. How
> does that occur and for what mechanical reason?

eh? so why do you advocate tension "as high as the rim can bear"?

>
> Not only is my recollection of failures different but I have a stack
> of more than 20 worn out MA-2 rims, none of which have cracks around
> spoke eyelets. These were wheels that I built to the maximum safe
> tension

which is what? this is the 3rd time of asking. it's important that you
answer what tension you use because spoke tension /does/ have a material
impact on rim cracking.

> that I arrived upon when I discovered that some people built
> wheels with too high spoke tension and whose wheels warped under hard
> braking, the only load that uniformly increases spoke tension in any
> part of the wheel.
>
> Cracked rims, in contrast, appeared suddenly with the arrival of hard
> and thickly anodized rims, the most obvious one being the MA-40 that
> is identical to the non-cracking MA-2 except for the anodizing.

but jobst, as we've discussed before, many times, the cracking does
/not/ emanate from the the radial cracks associated with anodizing.
cracking is almost always circumferential, or axial with the extrusion
axis, the weakest vein of the material. these cracks are frequently
/not/ centered on the spoke hole, therefore they /cannot/ be initiating
at the radial cracks resulting from any anodizing cracks. to argue
otherwise displays a /fundamental/ misunderstanding of the situation -
anodizing is NOT the cause!

time the ma40's arrival with cassette hubs and their more extreme dish,
and you have a strange coincidence, yes? mount an ma2 on a cassette hub
and it cracks, as has been cited here. an even more strange
coincidence? yet you still don't care to acknowledge anything that
disagrees with you.

the only "evidence" you've ever cited for "anodizing causes rim
cracking" is a dye penetrant test, something that is laughably
inappropriate - it only tells you existence, not cause. why do you
bluster and blow about stuff like this when all you're doing is
confirming that you don't know what you're talking about? most
engineers have to study basic materials science - where were you for
those classes? why would you want to hold forth on subjects you don't
know, get it wrong, and /still/ keep plowing on about it? what
intellectual issues do you have that prevents you from even basic
research on the internet or visiting a decent library? there's the
mechanics institute library in san francisco, a short hop for you - you
really need to make a visit some time. it's free.

> Other
> brands that offered hard anodized rims also had cracking problems, so
> much so that whole rims separated along the inner chamber, having
> thinner walls than the braking surface. That caused the tire to
> remain on the thicker walled outer portion and being without sockets,
> the inner portion was left attached to the spokes.

symptoms, not cause. typical jobstian "bait the fabricated edifice with
a meagre fact" argument. an entertaining device to be sure, but hardly
appropriate for an "expert" anxious to demonstrate competence.

>
> We have not made progress in that department. Few rims today have
> sockets that distribute spoke loads to both walls and some not even
> eyelets, meanwhile anodizing is still used although more sparingly.
>
> [email protected]

 

[Joe Riel]

[email protected] writes:

> What pictures?

> Do they show a sequence of side-to-side sway?

The ones you mentioned (I think) at smallchainring.com,
when looking for sideshots. Some of the photos were front views.
No sequences, so we cannot ascertain the maximum lean, however,
none showed any significant lean.

>
> I've been wondering about how much actual side-tilt there is
> and whether I've been fooled by the shoulder-drop when the
> rider sort of twists and curls down (rather than to the
> side) toward the foot at the bottom of the stroke.

I believe that there is a lot less lean than people imagine.
Certainly one can exaggerate the lean, but when you are
doing it naturally, the bike doesn't move all that much.
Certainly the total horizontal motion of the top tube is
less than 12 inches (side to side).

Joe

 

[[email protected]]

Jay Beattie wrote:
> My PX10 came with Monthlery Pros, which were a 400 gram tubular
> rim -- the same weight as my current Aeorohead OC clincher rim.
> Other models of the Monthlery were lighter, though. The relative
> light rims on the PX10 made little difference in the grand scheme
> of things because of the (felt like) three pound Simplex seat
> post, Pivo stem and boat-anchor Ideal leather saddle.

This was at a time when the standard Peugeot ten speeds came with steel
rims (clinchers, of course), steel cottered cranks and, IIRC, steel
handlebars.

 

[Sheldon Brown]

I wrote:

>>Back in the '70s and early '80s, nipples pulling through the rim
>>were exceedingly uncommon, and the usual cause of spoke breakage was
>>insufficient spoke tension. Tensiometers were not generally
>>available, and John provided a useful service by offering a way an
>>inexperienced wheelbuilder could get some idea of correct spoke
>>tension.
>
Jobst Brandt wrote:
>
> I am not aware of spoke failure caused by insufficient tension. How
> does that occur and for what mechanical reason?

Fatigue. I know you seem to think that the only cause of spoke fatigue
is inadequate stress relief. You may even be correct in this, and these
failures may result from the fact that it's impossible to stress relieve
spokes that have too low an initial tension.

I do know that back before you explained the metallurgy of stress relief
in spokes, wheels with low tension and stainless spokes suffered fatigue
failure much more often than wheels with higher tension.

(Despite an imperfect understanding of the microstructural results of
stress relieving, it is a practice that good wheelbuilders have followed
for many decades, even if they called it by another name.)

Sheldon "Relief" Brown
+------------------------------------------------------+
| What signifies knowing the names if you know not |
| the natures of things? -- Benjamin Franklin |
+------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Sheldon Brown]

I wrote:

>>John could be clearer in his use of the word "tension." He uses this
>>not in the sense of absolute tension (pounds or dynes) but tension per
>>cross-sectional area (PSI or dynes/cm2.)
>
Luns Tee asked:

> Why not use the proper word for this instead of fuzzying up the
> meaning of another? Force per unit area is stress.

I can't speak for John, but the reason I didn't use the term "stress" is
'cause I didn't think of it.

Sheldon "Stress Free" Brown
+-------------------------------------------------------------+
| Want of care does us more damage than want of knowledge. |
| -- Benjamin Franklin |
+-------------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Sheldon Brown]

I trolled:

>>"Serious" cyclists have always preferred clinchers.
>
A mysterious stranger replied:
>
> Recalling the dim past, no, most of the cyclists that I knew then (even
> before the time I spent in Germany, where I did a lot of cycling with
> pros) that could afford the good bikes were riding tubulars, that's
> what they were equipped with. Remember the PX10? It was a common
> high-end production bike and its rims were light by today's standards.

You said it yourself, "high-end."

Back in the day, your PX-10 would have been probably snazzier than 99.9%
of the bikes on the road, most of which were heavy steel one- or
three-speeds.

> Some people may have bought them as status symbols but everyone I knew
> who had these types of bikes just loved cycling. The people who did a
> lot of riding on top quality bikes rode tubulars.

I think you must have been in a sporty circle. This was also true of
most of my cycling friends, and I rode tubs myself...tough to resist
when I could buy Criterium Setas for $11. However we and our respective
circles werer pretty much elite compared to the general run of bicycle
users worldwide.
>
>>Amateur racing is hardly "serious" cycling, and there is no sigificant
>>pro racing in the U.S.. ;-)
>
> We'll have to agree to disagree on the definition of serious.
> Personally, I think John Howard was pretty serious. I think the German
> amateurs I knew who aspired to be pros were pretty serious, too. For
> the life of me, I can't tell why someone who rides 300mi./wk. trying to
> become a better racer can't be considered serious because they never
> reach the pro ranks. That really is an elitist view of our sport that
> is pretty insulting to tens of thousands of cyclists.
>
> Here's my definition of "serious": anyone who says (with sincerity,
> obviously) they are.

This is a bit of a hot-button issue for me. To me, a "serious" cyclist
is one who uses a bicycle for transportation, not just for recreation.

Most of the world's cyclists (thought probably a minority of readers of
this Newsgroup) fall into this group. There's nothing much more serious
than going to work in the morning.

The idea that racing cyclists are "superior" to those who "just" ride to
get to where they're going is what strike me as elitist.

Sheldon "Commuter" Brown
+------------------------------------------------------+
| It were not best that we should all think alike; |
| it is difference of opinion that makes horse-races. |
| -- Mark Twain |
+------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Sheldon Brown]

I wrote:
>
>>I used to use this system myself, before I got a tensiometer (I made a
>>cassette tape with a couple of piano notes on it, since the shop I
>>worked at at the time didn't possess a piano.)

Carl Fogel wrote:

Dear Sheldon,
>
> Surely Harris Cyclery is equipped with a Park Tools
> Spoke-Tuning Piano or a Hozan Harpsichord to check the
> tensiometer, but I can't find the part number for either
> instrument.

Dear Carl,

The cassette system was used when I worked at a different shop.

Here at Harris Cyclery we have a 4 manual Aeolian-Skinner pipe organ for
this. I usually use the "diapason" stop.

Instead of comparing the spoke tone to the organ tone by ear, we use a
Hewlett-Packard ocilloscope.

Sheldon "Das Wohltempierte Rad" Brown
+---------------------------------------------+
| All you need is ignorance and confidence; |
| then success is sure. --Mark Twain |
+---------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Joe Riel]

Joe Riel <[email protected]> writes:

> I believe that there is a lot less lean than people imagine.
> Certainly one can exaggerate the lean, but when you are
> doing it naturally, the bike doesn't move all that much.
> Certainly the total horizontal motion of the top tube is
> less than 12 inches (side to side).

Allow me to revise this. It may be a bit more than 12 inches side to
side. To estimate how much I tilt the bike, I attached a metal
rod to the seat stay. The lower end of the rod was near the ground.
I then bent the rod to an appropriate angle, climbed a hill, listening
for the tip to scrape the ground, then rebent it so that it would only
occasionally scrape during slightly exagerrated, but not unrealistic,
out-of-the-saddle climbing. I then measured how far I had to lean the
bike from vertical for the tip to scrape. Seven inches. So a
ballpark figure for total side to side movement is 14 inches.
Undoubtedly some people will do more than this. My top tube is 31
inches off the ground.

To check the effect of spoke tension, I leaned the bike to the right,
against a wall at that angle, stood, facing backwards, on the left
side of the bottom bracket, and reached down to pluck a lower right
hand side spoke. I could detect no significant change (less than a
semitone) between that and with the bike unloaded. As expected there
was a clear decrease in the pitch of the left side bottom spokes.

Joe

 

[Marvin]

[email protected] wrote:
> Marvin Meredith writes:
>
> >>>>>>> On the road, however, the rear wheel is not displaced by
> >>>>>>> laterally loading the rim at the brake, which minimizes the
> >>>>>>> required force. The forces involved may require substantial
> >>>>>>> changes in spoke tension. That has to be shown.
>
> >>>>>> I agree and that is easily done. I suggest that you stand on
> >>>>>> the pedals and lean the bicycle to the side, as one does when
> >>>>>> pedaling on a hill, and do a tone test. You'll find that there
> >>>>>> is no significant change in tension of the upper spokes (the
> >>>>>> ones near the brake pad).
>
> >>> But as any good student of the Bicycle Wheel will know, tension
> >>> changes from ground contact only affect the bottom few spokes in
> >>> any significant manner. Surely it's those we ought to be
> >>> measuring?
>
> >> I think I said that and you quote that below at "Oops".
>
> > Yes, we should measure the lower spokes, which I was doing anyway.
> > You said ten lines above there's no change in tension of the *upper*
> > spokes. Was this a completely unrelated fact, or were you trying to
> > confuse the issue?
>
> No, because the suggestion was made that the upper spokes are the ones
> that increase in tension. To prove that contention, the writer
> suggested pushing the rim sideways manually until it touched the brake
> pad. The point is that up there, even with off axis loading, no
> significant (audible) increase in tension occurs. That's where this
> thread began. The proponents of this tack have changed the approach
> since that venue collapsed.

Actually, the original (way back in the mists of time) contention was
from John Allen's website, which simply states that "lateral loading
while leaning the bicycle from side to side while pedaling out of the
saddle causes significant increases in spoke tension". You took
offence at that passage, as I recall, and invited people to check for
themselves. It's all in the google archives, but to be honest I can't
be bothered retracing the entire conversation in a game of
he-said-she-said.

I think the conclusion is that leaning the bike so the spokes are some
way past vertical will increase the tension in the opposite spoke. The
only contention is whether this lean occurs in normal riding.

> >>>>>> This is a false visualization of spoke stresses similar to "the
> >>>>>> wheel hangs from the top spokes" scenario. The change lies in
> >>>>>> the amount of slackening of left and right spokes at the ground
> >>>>>> contact zone.
>
> >>>>> I'm not convinced here. I'll accept (as in the Bicycle Wheel)
> >>>>> that spokes lose tension from a radial load, so the spokes at
> >>>>> the bottom of a wheel are the lightest loaded. I'll also accept
> >>>>> that lateral loading has no overall effect, only to change the
> >>>>> balance between left and right side spokes. This obviously
> >>>>> means one side increases in tension relative to the other.
>
> >>>> Oops! No, that is not the case. One side loses more tension
> >>>> than the other and only at the ground contact zone. You needn't
> >>>> take this on faith. It is easy to test as has been explained.
>
> >>> Yes, I just tested it and got exactly the result I expected -
> >>> higher tension in the spokes nearest the ground. Perhaps we're
> >>> measuring different things, so I'll describe this in painstaking
> >>> detail.
>
> >> How far did you lean the bicycle? No doubt as the lean angle get
> >> large, larger than when riding, it starts becoming more a side load
> >> on the wheel similar to pushing the rim sideways at the brake
> >> bridge.
>
> > At the risk of sounding like jim beam, first you were loudly
> > asserting that there was *no* change in tension due to lateral
> > loads, which we now know isn't the case. Now it's lateral loads
> > encountered during "normal" riding. When I tell you my "normal"
> > riding style involves a fair amount of bike sway, especially during
> > sprinting, doubtless you'll further "clarify" your position.
>
> I WHAT! I said nothing of the kind. I said at the brake bridge there
> was no change. Let's not change horses in the middle of the wheel.

Ach, mental typo. I meant that you'd asserted there was no *increase*
in tension. Mea culpa.

> > In point of fact, the above test was done leaning the bike as far as
> > I "normally" would, although propping up against a wall is never the
> > most accurate gauge of such things. I'll try sighting through the
> > front hub when I go to work (which should have been five minutes
> > ago).

Having spent most of the journey to work staring at my front hub
instead of watching the traffic, I'll accept that most riding doesn't
cause the spokes to go past vertical. However, high-cadence sprinting
or low-cadence grinding uphill (can you tell I ride a fixie?)
definitely get the front spokes over vertical. A geared rear wheel
would obviously be worse.