Spoke tension meter

[Peter Cole]

Sandy wrote:
>
> 2) that your rhetorical style does very little to explain or convince, and
> that your supporters (save Luns Tee) support on faith, not reasoning, as
> though you were the newest creator of bicycle myth and lore.

Not to take anything away from Luns, who I credit as much for remarkable
patience and restraint as much as technical knowledge and communication
skills, but I think your classification of the other "supporters" is
more than a bit condescending.

I think the would-be critics are mostly missing the point. The primary
question is whether there is residual stress in the spokes of a typical
newly built wheel -- either pre-existing in the spokes, or created in
the spokes during lacing/tensioning.

If there is residual stress, and it is near yield locally, then it
follows that load cycles will cause fatigue failures. It also follows
that any stress relief process that lowers these residuals will prolong
spoke fatigue life.

Mechanical stress relief is a well-known process, as is thermal stress
relief and vibrational stress relief. Mechanical stress relief is the
only process that is practical in this context.

This is only made complicated by people whose sole agenda is to snipe at
Jobst for personal reasons the rest of us can only guess at.

 

[41]

jim beam wrote:
> 41 wrote:

> > ========================================================================
> > FRESH SPOKES from JIM BEAM & Company- A fresh idea for your wheels!
> >
> > Like a fine whine, spokes become more stressful as t hey go on and on
> > and on. It may take a second or it may take about a week- we can't say
> > how we get those figures- but fresh spokes soon become stale, and like
> > a stale loaf of bread, any attempt to mechanically stress relieve them
> > can inste ad lead to even more badness, under unspecified circumstances.
> > But not any more! With our patented EVASION process, we can now deliver
> > to you FACTORY FRESH spokes for your lacing pleasure! Here at JIM BEAM
> > & Company, we use a neutron thingy an d our own special secret science
> > to find the interstitials, the alloy systems, the grain size, and the
> > logical disconnect density. Then we date-stamp every spoke before
> > air-expressing them off to you. Your bread and your milk come with
> > "be st before" dates, why not your spokes? We use only stainless steel
> > spokes, which we then anodize, and then we weld and machine the
> > breaking surfaces, for extra safety.
> >
> > Fresh spokes and ********- from JIM BEAM... and company!
> >
> > CALL and inquire about our Usenet stalking specials. Psychopathic
> > creepiness assured.
> > =========================================================================p
> >
>
> google "strain ageing": 207,000 hits.
>
> http://www.steeluniversity.org/content/html/eng/default.asp?catid=139&pageid=2081271364
>
> idiot.

BZZZT.
I figured the long delay for you to produce anything even resembling an
answer was because you had to run over to your mother's basement for
your undergraduate notes, or to remember the term needed for a Google
search. As typical for you, you throw around fancy terms and web pages,
but without taking the time to read them or to understand the ideas.

To take only the most obvious point. Do you really think any reasonably
high quality stainless steel spoke has been manufactured so poorly so
as to be subject to any important strain ageing? Tip: in your own
reference, which you obviously didn't read, check out ways to eliminate
strain ageing- which is essentially what the whole section was about.
Spokes are high quality, ductile, and do not go stale. You have vaguely
remembered some undergraduate lecture but haven't been able to put it
into context or assess its relevance- which, for the matter at hand, is
essentially zero.

========================================================================
Fresh spokes and an ever growing pile of ********- from JIM BEAM... and
company!

CALL and inquire about our Usenet stalking specials. Psychopathic
creepiness assured.
=========================================================================

 

[Joe Riel]

[email protected] writes:

> Given that the usual idea is to squeeze two pairs of spokes
> together at once, one pair on either side of the wheel, does
> 100 lbs of squeeze seem like a reasonable amount?

The grip strength of an average male is about 100 lbf, if I recall
correctly, so this seems a reasonable value. I had my grip measured a
year ago and it was around this value---somewhat surprising because
not only am I on the thin side but was still recovering from a
serious ailment and was thinner and weaker than usual. Squeezing
spokes might not permit achieving maximum grip, however, lacking
other data I'll go with it.


Joe

 

[dvt]

[email protected] wrote:
> In 1983, Jobst's 1st edition apparently
> showed that spokes broke without much elongation in tensile
> testing, since the 2nd edition in 1988 says so and goes on
> to detail how newer spokes stretched dramatically in the
> same sort of tensile testing.

I don't have either of those editions handy. Here are two possible
explanations of that data.

1. Earlier spokes (1983 edition) had residual stress, causing them to
fail at the points of high residual stress before the rest of the spoke
reached yeild. Later spokes (1988 edition) didn't have these regions of
high remanent stress, which led to the entire spoke reaching yield at
the same time. The reduction might be explained by a change in
manufacturing process or a change to a material that is somehow immune
to residual stress.

2. New and old spokes had little residual stress, but spoke
manufacturers switched to a less brittle material.

There may be other explanations that my limited imagination has failed
to foresee. If you assume explanation 1 is true, then perhaps newer
spokes do not require stress relief. If you assume explanation 2 is
true, then spokes never required stress relief.

It's still possible, however, that the process of building a wheel
produces residual stress in the spoke. In that case, stress relief would
be helpful.

I know this is still not conclusive about the effectiveness of stress
relief, but it might help us ask the right questions.

> Of course, the actual improvement seems to be even more
> dramatic--in only ten years, the same spokes seemed to
> become much less likely to fail. It's been suggested that
> the early 1980's happened to be a time in which all sorts of
> improvements in metallury became widespread.

I think that's pretty normal growth. Technology often grows in discrete
steps, rather than a gradual refinement. If you looked at it on a longer
time scale (say, f'rinstance, 100 years), a chart of "goodness" vs. time
might look smooth. But if you expand the time scale to 10 or 20 years,
you'll likely begin to see some discrete steps.

Not all technology follows this rule o' thumb. Computer speed is a good
example, advances being quite rapid in recent years. If you were to
chart computer speed vs. time, you'd probably see a smooth looking curve
at a scale of 10 years, but a set of discrete steps over 1-2 years.

--
Dave
dvt at psu dot edu

 

[[email protected]]

On Sun, 26 Jun 2005 15:10:26 GMT, Joe Riel
<[email protected]> wrote:

>[email protected] writes:
>
>> Given that the usual idea is to squeeze two pairs of spokes
>> together at once, one pair on either side of the wheel, does
>> 100 lbs of squeeze seem like a reasonable amount?
>
>The grip strength of an average male is about 100 lbf, if I recall
>correctly, so this seems a reasonable value. I had my grip measured a
>year ago and it was around this value---somewhat surprising because
>not only am I on the thin side but was still recovering from a
>serious ailment and was thinner and weaker than usual. Squeezing
>spokes might not permit achieving maximum grip, however, lacking
>other data I'll go with it.
>
>
>Joe

Dear Joe,

A belated peek at the index of McMahon and Graham's 1992
"The Bicycle and the Walkman" led me to their section 3.3 on
the measurement of stress and strain in bicycle spokes.

Figure 3.5 shows two stress-strain graphs, one for stainless
steel and one for carbon steel spokes, with the vertical
scale in pounds and psi and the horizontal scale in 0.001"
extension for an originally 1-inch section of 2 mm spoke,
with nicely drawn dashed lines from 0.002 at the same
initial slope to show where the 0.2% plastic strain
intersects the test data:

| .
| .
| . /
| . /
| . /
| . /
| . /
|____/_____________________
0.002"

Below are their equations from example 3.2 on page 29, which
I may have vaguely remembered when I used the 600 lb yield
figure--their graphs are roughly similar to Jobst's tensile
tests.

Carl Fogel

Q. For the stress-strain curve of the stainless-steel spoke
shown in Fig. 3.5, show how the 0.2% yield stress and the
total strain at this stress are calculated. The spoke
diameter is 2mm (0.08in).

A. The load at which the stress-strain curve crosses the
line representing a plastic strain of 0.002 is 2578 N (600
lb). Notethat this line has a slope equal to E, 210 GPA
(30x10^6psi). Since the cross-sectional area is 3.14mm^2
(0.005in^2), the yield stress is:

load at 0.2% plastic offset 2578N
----------------------------- = -------------- =
original cross-sectional area 3.14x10^-6mm^2

821MPa (119,000psi)

[E below is epsilon]

The total strain (Et) = elastic strain (Ee) + plastic strain
(Ep). At yielding, Ep = 0.002 and Ee = 821 MPa/210 GPa =
0.004. Therefore, Et = 0.006.

 

[jim beam]

41 wrote:
>
> jim beam wrote:
>
>>41 wrote:
>
>
>>>========================================================================
>>>FRESH SPOKES from JIM BEAM & Company- A fresh idea for your wheels!
>>>
>>>Like a fine whine, spokes become more stressful as t hey go on and on
>>>and on. It may take a second or it may take about a week- we can't say
>>>how we get those figures- but fresh spokes soon become stale, and like
>>>a stale loaf of bread, any attempt to mechanically stress relieve them
>>>can inste ad lead to even more badness, under unspecified circumstances.
>>>But not any more! With our patented EVASION process, we can now deliver
>>>to you FACTORY FRESH spokes for your lacing pleasure! Here at JIM BEAM
>>>& Company, we use a neutron thingy an d our own special secret science
>>>to find the interstitials, the alloy systems, the grain size, and the
>>>logical disconnect density. Then we date-stamp every spoke before
>>>air-expressing them off to you. Your bread and your milk come with
>>>"be st before" dates, why not your spokes? We use only stainless steel
>>>spokes, which we then anodize, and then we weld and machine the
>>>breaking surfaces, for extra safety.
>>>
>>>Fresh spokes and ********- from JIM BEAM... and company!
>>>
>>>CALL and inquire about our Usenet stalking specials. Psychopathic
>>>creepiness assured.
>>>=========================================================================p
>>>
>>
>>google "strain ageing": 207,000 hits.
>>
>>http://www.steeluniversity.org/content/html/eng/default.asp?catid=139&pageid=2081271364
>>
>>idiot.
>
>
> BZZZT.
> I figured the long delay for you to produce anything even resembling an
> answer was because you had to run over to your mother's basement for
> your undergraduate notes, or to remember the term needed for a Google
> search. As typical for you, you throw around fancy terms and web pages,
> but without taking the time to read them or to understand the ideas.

point is, why don't /you/ do a google search? presumably because you're
not interested in the tech, just being a troll.

>
> To take only the most obvious point. Do you really think any reasonably
> high quality stainless steel spoke has been manufactured so poorly so
> as to be subject to any important strain ageing? Tip: in your own
> reference, which you obviously didn't read, check out ways to eliminate
> strain ageing- which is essentially what the whole section was about.
> Spokes are high quality, ductile, and do not go stale.

hmm. what is "high quality stainless steel" exactly? as for equating
ageing with the word "stale", that's trollspeak. i'll talk tech with
you, but it doesn't seem you want that.

> You have vaguely
> remembered some undergraduate lecture but haven't been able to put it
> into context or assess its relevance- which, for the matter at hand, is
> essentially zero.
>
> ========================================================================
> Fresh spokes and an ever growing pile of ********- from JIM BEAM... and
> company!
>
> CALL and inquire about our Usenet stalking specials. Psychopathic
> creepiness assured.
> =========================================================================
>

 

[[email protected]]

On Sun, 26 Jun 2005 09:08:08 -0400, Peter Cole
<[email protected]> wrote:

>Sandy wrote:
>>
>> 2) that your rhetorical style does very little to explain or convince, and
>> that your supporters (save Luns Tee) support on faith, not reasoning, as
>> though you were the newest creator of bicycle myth and lore.
>
>Not to take anything away from Luns, who I credit as much for remarkable
>patience and restraint as much as technical knowledge and communication
>skills, but I think your classification of the other "supporters" is
>more than a bit condescending.
>
>I think the would-be critics are mostly missing the point. The primary
>question is whether there is residual stress in the spokes of a typical
>newly built wheel -- either pre-existing in the spokes, or created in
>the spokes during lacing/tensioning.
>
>If there is residual stress, and it is near yield locally, then it
>follows that load cycles will cause fatigue failures. It also follows
>that any stress relief process that lowers these residuals will prolong
>spoke fatigue life.
>
>Mechanical stress relief is a well-known process, as is thermal stress
>relief and vibrational stress relief. Mechanical stress relief is the
>only process that is practical in this context.
>
>This is only made complicated by people whose sole agenda is to snipe at
>Jobst for personal reasons the rest of us can only guess at.

Dear Peter,

Nicely put, particularly your third paragraph about local
yield.

But there is at least one other complication--how did spokes
become enormously more durable within ten years of the 1st
edition of Jobst's book of 1983, as mentioned in his 3rd
edition of 1993?

What happened to the residual stresses?

If the residual stresses were still present, did
improvements in the spoke material render them largely
unimportant?

(The notable change in his tensile tests between the 1st
edition of 1983 and the 2nd edition of 1988 suggests that
the spoke material did indeed change. I wonder if 2005
spokes might show even more improvement--after all, the
steel industry and spoke makers have had 17 more years to
make quiet improvements.)

If the residual stresses largely vanished, what was the
cause? Some new forming process? Subtle changes in hub
holes, spoke elbows, threads, or nipples that led to reduced
"spoke-line correction"? (Recent posts suggest that the tiny
bends made by wheel builders may--annoyingly--cause much
more residual stress than the big elbow bend made by the
factory.)

Carl Fogel

 

[Benjamin Lewis]

dvt wrote:

> It's still possible, however, that the process of building a wheel
> produces residual stress in the spoke. In that case, stress relief would
> be helpful.

Possible? I increased the tension in a spoke in my wheel and it yielded.
What more do you want?

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening

 

[Peter Cole]

[email protected] wrote:

> But there is at least one other complication--how did spokes
> become enormously more durable within ten years of the 1st
> edition of Jobst's book of 1983, as mentioned in his 3rd
> edition of 1993?
>
> What happened to the residual stresses?

I don't know that anything happened. I had spokes fail in old wheels,
and, before I started stress relieving, I had spokes fail in new wheels.


> If the residual stresses were still present, did
> improvements in the spoke material render them largely
> unimportant?

A different alloy might have intrinsically better fatigue life.
Manufacturing (wire and/or spoke) may have improved. Who cares? The
question is academic (since most of us are not using any old spokes) and
neither the alloys of the old and new nor the manufacturing processes
are known, so how could this question ever be answered?

>
> (The notable change in his tensile tests between the 1st
> edition of 1983 and the 2nd edition of 1988 suggests that
> the spoke material did indeed change. I wonder if 2005
> spokes might show even more improvement--after all, the
> steel industry and spoke makers have had 17 more years to
> make quiet improvements.)

My old spokes were zinc plated carbon steel. My newer ones are
stainless. Most of my newer ons are also butted. How can I compare? Who
cares?

> If the residual stresses largely vanished, what was the
> cause? Some new forming process? Subtle changes in hub
> holes, spoke elbows, threads, or nipples that led to reduced
> "spoke-line correction"?

You're giving hypothetical answers to hypothetical questions.

> (Recent posts suggest that the tiny
> bends made by wheel builders may--annoyingly--cause much
> more residual stress than the big elbow bend made by the
> factory.)

I don't follow. I missed that point if anybody attempted to make it.

 

[dvt]

Benjamin Lewis wrote:

> dvt wrote:
>>It's still possible, however, that the process of building a wheel
>>produces residual stress in the spoke. In that case, stress relief would
>>be helpful.

> Possible? I increased the tension in a spoke in my wheel and it yielded.
> What more do you want?

I haven't been convinced that yielding a spoke at the elbow is evidence
of residual stress. Another plausible explanation is that the geometry
of the spoke/hub interface caused a stress concentration at the elbow,
causing the elbow to bend until it bedded in.

Maybe we're at a difference of terms -- perhaps the scenario I just
described is something you'd call residual stress. I wouldn't use that
term, preferring to call it a stress concentration, but either way, we
may be talking about the same idea.

Many of the arguments I see on R.B.Tech boil down to semantics when the
terms are well-defined.

--
Dave
dvt at psu dot edu

 

[[email protected]]

On Sun, 26 Jun 2005 15:29:34 -0400, Peter Cole
<[email protected]> wrote:

>[email protected] wrote:
>
>> But there is at least one other complication--how did spokes
>> become enormously more durable within ten years of the 1st
>> edition of Jobst's book of 1983, as mentioned in his 3rd
>> edition of 1993?
>>
>> What happened to the residual stresses?
>
>I don't know that anything happened. I had spokes fail in old wheels,
>and, before I started stress relieving, I had spokes fail in new wheels.
>
>
>> If the residual stresses were still present, did
>> improvements in the spoke material render them largely
>> unimportant?
>
>A different alloy might have intrinsically better fatigue life.
>Manufacturing (wire and/or spoke) may have improved. Who cares? The

^^^^^^^^^^
>question is academic (since most of us are not using any old spokes) and
>neither the alloys of the old and new nor the manufacturing processes
>are known, so how could this question ever be answered?
>
>>
>> (The notable change in his tensile tests between the 1st
>> edition of 1983 and the 2nd edition of 1988 suggests that
>> the spoke material did indeed change. I wonder if 2005
>> spokes might show even more improvement--after all, the
>> steel industry and spoke makers have had 17 more years to
>> make quiet improvements.)
>
>My old spokes were zinc plated carbon steel. My newer ones are
>stainless. Most of my newer ons are also butted. How can I compare? Who

^^^
>cares?
^^^^^
>
>> If the residual stresses largely vanished, what was the
>> cause? Some new forming process? Subtle changes in hub
>> holes, spoke elbows, threads, or nipples that led to reduced
>> "spoke-line correction"?
>
>You're giving hypothetical answers to hypothetical questions.
>
>> (Recent posts suggest that the tiny
>> bends made by wheel builders may--annoyingly--cause much
>> more residual stress than the big elbow bend made by the
>> factory.)
>
>I don't follow. I missed that point if anybody attempted to make it.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Dear Peter,

Let me try your logic . . .

Who cares?

Carl Fogel

 

[Benjamin Lewis]

dvt wrote:

> Benjamin Lewis wrote:
>
>> dvt wrote:
>>> It's still possible, however, that the process of building a wheel
>>> produces residual stress in the spoke. In that case, stress relief
>>> would be helpful.
>
>> Possible? I increased the tension in a spoke in my wheel and it
>> yielded. What more do you want?
>
> I haven't been convinced that yielding a spoke at the elbow is evidence
> of residual stress. Another plausible explanation is that the geometry
> of the spoke/hub interface caused a stress concentration at the elbow,

That's residual stress.

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening

 

[jim beam]

dvt wrote:
> Benjamin Lewis wrote:
>
>> dvt wrote:
>>
>>> It's still possible, however, that the process of building a wheel
>>> produces residual stress in the spoke. In that case, stress relief
>>> would be helpful.
>
>
>> Possible? I increased the tension in a spoke in my wheel and it yielded.
>> What more do you want?
>
>
> I haven't been convinced that yielding a spoke at the elbow is evidence
> of residual stress. Another plausible explanation is that the geometry
> of the spoke/hub interface caused a stress concentration at the elbow,
> causing the elbow to bend until it bedded in.

yes, stress at the elbow results from the fact that the spoke does not
have a purely axial load. that's why a lot of pre-built wheels now have
straight pull spokes - it addresses this fundamental problem.

>
> Maybe we're at a difference of terms -- perhaps the scenario I just
> described is something you'd call residual stress. I wouldn't use that
> term, preferring to call it a stress concentration, but either way, we
> may be talking about the same idea.
>
> Many of the arguments I see on R.B.Tech boil down to semantics when the
> terms are well-defined.
>

 

[jim beam]

Benjamin Lewis wrote:
> dvt wrote:
>
>
>>Benjamin Lewis wrote:
>>
>>
>>>dvt wrote:
>>>
>>>>It's still possible, however, that the process of building a wheel
>>>>produces residual stress in the spoke. In that case, stress relief
>>>>would be helpful.
>>
>>>Possible? I increased the tension in a spoke in my wheel and it
>>>yielded. What more do you want?
>>
>>I haven't been convinced that yielding a spoke at the elbow is evidence
>>of residual stress. Another plausible explanation is that the geometry
>>of the spoke/hub interface caused a stress concentration at the elbow,
>
>
> That's residual stress.
>
no, it's applied stress - it results from the structure and would
disappear if the wheel were disassembled. this is the problem with
traditional spokes vs. straight pull spokes - there is a fundamentally
unavoidable bending load on the spoke elbow. straight pull spokes don't
have it. "stress relief" cannot cure it.

 

[jim beam]

Peter Cole wrote:
> [email protected] wrote:
>
>> But there is at least one other complication--how did spokes
>> become enormously more durable within ten years of the 1st
>> edition of Jobst's book of 1983, as mentioned in his 3rd
>> edition of 1993?
>>
>> What happened to the residual stresses?
>
>
> I don't know that anything happened. I had spokes fail in old wheels,
> and, before I started stress relieving, I had spokes fail in new wheels.
>
>
>> If the residual stresses were still present, did
>> improvements in the spoke material render them largely
>> unimportant?
>
>
> A different alloy might have intrinsically better fatigue life.
> Manufacturing (wire and/or spoke) may have improved. Who cares? The
> question is academic (since most of us are not using any old spokes) and
> neither the alloys of the old and new nor the manufacturing processes
> are known, so how could this question ever be answered?

differences between old & new /are/ well known. modern fatigue
resistant steels are frequently vacuum degassed, and this process is
used for modern spoke wire. it results in much lower inclusion counts
which consequently means fewer fatigue initiation points. whether this
is convenient to "stress relief" theory or not, vacuum degassing is well
documented to improve fatigue life [unlike "stress relief" in highly
cold worked tensile wire] and electron microscopy has proven fatigue
initiation on micro-inclusions that were not visible with optical
microscopy. why else would a manufacturer go to the [considerable]
expense of specifying this kind of material if ordinary stainless would do?

>
>>
>> (The notable change in his tensile tests between the 1st
>> edition of 1983 and the 2nd edition of 1988 suggests that
>> the spoke material did indeed change. I wonder if 2005
>> spokes might show even more improvement--after all, the
>> steel industry and spoke makers have had 17 more years to
>> make quiet improvements.)
>
>
> My old spokes were zinc plated carbon steel. My newer ones are
> stainless. Most of my newer ons are also butted. How can I compare? Who
> cares?
>
>> If the residual stresses largely vanished, what was the
>> cause? Some new forming process? Subtle changes in hub
>> holes, spoke elbows, threads, or nipples that led to reduced
>> "spoke-line correction"?
>
>
> You're giving hypothetical answers to hypothetical questions.
>
>> (Recent posts suggest that the tiny
>> bends made by wheel builders may--annoyingly--cause much
>> more residual stress than the big elbow bend made by the
>> factory.)
>
>
> I don't follow. I missed that point if anybody attempted to make it.

 

[[email protected]]

Dave vt? writes:

>> In 1983, Jobst's 1st edition apparently showed that spokes broke
>> without much elongation in tensile testing, since the 2nd edition
>> in 1988 says so and goes on to detail how newer spokes stretched
>> dramatically in the same sort of tensile testing.

> I don't have either of those editions handy. Here are two possible
> explanations of that data.

> 1. Earlier spokes (1983 edition) had residual stress, causing them
> to fail at the points of high residual stress before the rest of the
> spoke reached yield. Later spokes (1988 edition) didn't have these
> regions of high remnant stress, which led to the entire spoke
> reaching yield at the same time. The reduction might be explained by
> a change in manufacturing process or a change to a material that is
> somehow immune to residual stress.

> 2. New and old spokes had little residual stress, but spoke
> manufacturers switched to a less brittle material.

> There may be other explanations that my limited imagination has
> failed to foresee. If you assume explanation 1 is true, then
> perhaps newer spokes do not require stress relief. If you assume
> explanation 2 is true, then spokes never required stress relief.

> It's still possible, however, that the process of building a wheel
> produces residual stress in the spoke. In that case, stress relief
> would be helpful.

> I know this is still not conclusive about the effectiveness of
> stress relief, but it might help us ask the right questions.


I am riding DT spokes from that era now so you might include that
third possibility, that of stress relief being effective. My wheels
have Campagnolo Record hubs with un-curved QR levers that were common
more than 20 years ago, I don't know when they were last made. The
spokes and hubs were new at that time.

>> Of course, the actual improvement seems to be even more
>> dramatic--in only ten years, the same spokes seemed to become much
>> less likely to fail. It's been suggested that the early 1980's
>> happened to be a time in which all sorts of improvements in
>> metallurgy became widespread.

> I think that's pretty normal growth. Technology often grows in
> discrete steps, rather than a gradual refinement. If you looked at
> it on a longer time scale (say, f'rinstance, 100 years), a chart of
> "goodness" vs. time might look smooth. But if you expand the time
> scale to 10 or 20 years, you'll likely begin to see some discrete
> steps.

> Not all technology follows this rule o' thumb. Computer speed is a
> good example, advances being quite rapid in recent years. If you
> were to chart computer speed vs. time, you'd probably see a smooth
> looking curve at a scale of 10 years, but a set of discrete steps
> over 1-2 years.

I think it is important to note that these stress relieving subject
threads often start after someone complains about spokes breaking in a
name brand wheel, so spokes still break.

[email protected]

 

[[email protected]]

Benjamin Lewis writes:

>> It's still possible, however, that the process of building a wheel
>> produces residual stress in the spoke. In that case, stress relief
>> would be helpful.

> Possible? I increased the tension in a spoke in my wheel and it
> yielded. What more do you want?

I think we have defined residual stress as that stress not related to
spoke tension but to forming the spoke in manufacture and wheel
lacing. Even elbow angle modification from tensioning is not tensile
stress derived from spoke cross section and tensio,n but rather a
forming process. That is what residual stress is in this context.

[email protected]

 

[dvt]

[email protected] wrote:

> Dave vt? writes:

>>>In 1983, Jobst's 1st edition apparently showed that spokes broke
>>>without much elongation in tensile testing, since the 2nd edition
>>>in 1988 says so and goes on to detail how newer spokes stretched
>>>dramatically in the same sort of tensile testing.

>>I don't have either of those editions handy. Here are two possible
>>explanations of that data.
[snip explanations]

> I am riding DT spokes from that era now so you might include that
> third possibility, that of stress relief being effective.

I don't think that the difference in tensile tests (read that first
paragraph again) supports or violates your claim that stress relief is
effective.

> I think it is important to note that these stress relieving subject
> threads often start after someone complains about spokes breaking in a
> name brand wheel, so spokes still break.

No doubt about that!

--
Dave
dvt at psu dot edu

 

[Benjamin Lewis]

jobst brandt wrote:

> Benjamin Lewis writes:
>
>>> It's still possible, however, that the process of building a wheel
>>> produces residual stress in the spoke. In that case, stress relief
>>> would be helpful.
>
>> Possible? I increased the tension in a spoke in my wheel and it
>> yielded. What more do you want?
>
> I think we have defined residual stress as that stress not related to
> spoke tension but to forming the spoke in manufacture and wheel
> lacing. Even elbow angle modification from tensioning is not tensile
> stress derived from spoke cross section and tensio,n but rather a
> forming process. That is what residual stress is in this context.

Yes, but apparently a new disagreement on semantics has now started,
despite the fact that it has no bearing one what's going on. I think we're
back to another "wheel-doesn't-stand-on-spokes-I-don't-get-superposition"
thing.

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening

 

[jim beam]

[email protected] wrote:
> Dave vt? writes:
>
>
>>>In 1983, Jobst's 1st edition apparently showed that spokes broke
>>>without much elongation in tensile testing, since the 2nd edition
>>>in 1988 says so and goes on to detail how newer spokes stretched
>>>dramatically in the same sort of tensile testing.
>
>
>>I don't have either of those editions handy. Here are two possible
>>explanations of that data.
>
>
>>1. Earlier spokes (1983 edition) had residual stress, causing them
>>to fail at the points of high residual stress before the rest of the
>>spoke reached yield. Later spokes (1988 edition) didn't have these
>>regions of high remnant stress, which led to the entire spoke
>>reaching yield at the same time. The reduction might be explained by
>>a change in manufacturing process or a change to a material that is
>>somehow immune to residual stress.
>
>
>>2. New and old spokes had little residual stress, but spoke
>>manufacturers switched to a less brittle material.
>
>
>>There may be other explanations that my limited imagination has
>>failed to foresee. If you assume explanation 1 is true, then
>>perhaps newer spokes do not require stress relief. If you assume
>>explanation 2 is true, then spokes never required stress relief.
>
>
>>It's still possible, however, that the process of building a wheel
>>produces residual stress in the spoke. In that case, stress relief
>>would be helpful.
>
>
>>I know this is still not conclusive about the effectiveness of
>>stress relief, but it might help us ask the right questions.
>
>
>
> I am riding DT spokes from that era now so you might include that
> third possibility, that of stress relief being effective. My wheels
> have Campagnolo Record hubs with un-curved QR levers that were common
> more than 20 years ago, I don't know when they were last made. The
> spokes and hubs were new at that time.
>
>
>>>Of course, the actual improvement seems to be even more
>>>dramatic--in only ten years, the same spokes seemed to become much
>>>less likely to fail. It's been suggested that the early 1980's
>>>happened to be a time in which all sorts of improvements in
>>>metallurgy became widespread.
>
>
>>I think that's pretty normal growth. Technology often grows in
>>discrete steps, rather than a gradual refinement. If you looked at
>>it on a longer time scale (say, f'rinstance, 100 years), a chart of
>>"goodness" vs. time might look smooth. But if you expand the time
>>scale to 10 or 20 years, you'll likely begin to see some discrete
>>steps.
>
>
>>Not all technology follows this rule o' thumb. Computer speed is a
>>good example, advances being quite rapid in recent years. If you
>>were to chart computer speed vs. time, you'd probably see a smooth
>>looking curve at a scale of 10 years, but a set of discrete steps
>>over 1-2 years.
>
>
> I think it is important to note that these stress relieving subject
> threads often start after someone complains about spokes breaking in a
> name brand wheel, so spokes still break.

really? when i've asked posters about the spoke brand used in these
"brand name wheels", the answer has to date always been "unknown". so
in the absence of knowing the spoke quality, how can you equate spoke
failure with lack of stress relief? spoke quality has a /significant/
impact on fatigue life, so you can't claim cause & effect.

>
> [email protected]