Any other pros break spokes?

Quoted message said:

Floyd reportedly broke a spoke in yesterday's stage 4 of the Tour of
California.

"Then, at mile 65, Landis broke a spoke and stopped for a wheel
change."

http://www.velonews.com/race/dom/articles/9535.0.html

I seem to remember another Zipp wheel reportedly breaking a spoke in
pro race within the last year or two, but can't find the reference now.

Don't Zipp know about stress relieving? Or why else might the spoke
break? Do other pro tema's wheels break spokes any more?

Obviously you've never ridden in a close pack. Many spokes break because
they get caught in a skewer. Which is like stressrelieving, but a bit
more final 😉

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Dans le message de
news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et puis a déclaré
:

Quoted message said:

Floyd reportedly broke a spoke in yesterday's stage 4 of the Tour of
California.

"Then, at mile 65, Landis broke a spoke and stopped for a wheel
change."

http://www.velonews.com/race/dom/articles/9535.0.html

I seem to remember another Zipp wheel reportedly breaking a spoke in
pro race within the last year or two, but can't find the reference
now.

Don't Zipp know about stress relieving? Or why else might the spoke
break? Do other pro tema's wheels break spokes any more?

I suggest you put and answer these three questions in reverse order. It may
obviate the inherent criticism. Actual answers, only, please. Not
recitations from venerable and unreliable gossipy sources.
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

Quoted message said:

Floyd reportedly broke a spoke in yesterday's stage 4 of the Tour of
California.

"Then, at mile 65, Landis broke a spoke and stopped for a wheel
change."

http://www.velonews.com/race/dom/articles/9535.0.html

I seem to remember another Zipp wheel reportedly breaking a spoke in
pro race within the last year or two, but can't find the reference now.

Don't Zipp know about stress relieving? Or why else might the spoke
break? Do other pro tema's wheels break spokes any more?

The other main reasons why spokes break in 8/9/10s wheels are if they
have bends at the hub or nipple, which isn't a new problem, or when
spokes on the left side get completely unloaded in use all the time,
causing them to break from fatigue
(http://sheldonbrown.com/wheelbuild.html#half-radial). How this might
change with low-spoke count wheels where the left spokes can have a lot
more tension, but also get loaded more heavily because there's fewer
spokes, is something I'm unclear about. (Also, many of those wheels
have radial left spokes anyway, which according to the stance on
Sheldon's page would mostly eliminate the problem.. but I think it's
somewhat contentious whether torque load actually contributes to this
problem all that much.)

There's also the fact that some (I don't really know how many) of these
wheels have spokes with 200+ kgfs of tension, and some (none of the
former group, I think) have al spokes. I'm pretty sure that the crazy
high tension ones don't pose any problems to spoke durability beyond
making internal stresses that should be eliminated anyway much more
likely to cause breakage, but I could be wrong about this. Jobst has
said that the tension in highly tensioned spokes on conventional wheels
is something like a third of their tensile strength. So the question is
whether operating at more like two thirds of their tensile strength
would be okay.

As for aluminum spokes, I'm pretty happy to have not thought about it
very much.

Hope any of this helps... I also have questions about this stuff but
the truth is probably that boutique wheels aren't even designed by
people with clear understandings of any of this, which makes figuring
it all out kind of a lonely road.

Or hit a pothole/traffic turtle at 40+mph. There's some stresses going
on there, and they don't go away just because a wheel was stress
relieved.

In all my years racing and training I can't recall ever seeing a guy
break a spoke from contact of the skewer of another rider as long as
both bikes still have both wheels on the pavement.

Andrew F Martin said:

Or hit a pothole/traffic turtle at 40+mph. There's some stresses
going on there, and they don't go away just because a wheel was
stress relieved.

Tilt! Pot holes and other road hazards do not cause spoke breakage.
Wheel loading, other than few crashes, relax spoke tension, not
increase it. Failures in spokes are fatigue failures, not results of
singular overloads.

On that note. If you damage a wheel beyond repair, do not unspoke it
nor throw the spokes away. Lay a new rim of the same kind next to the
old and transfer the spokes one at a time to the new rim and true the
wheel. These spokes will most likely outlive a new set.

Jobst Brandt

Chris M Reynolds said:

In all my years racing and training I can't recall ever seeing a guy
break a spoke from contact of the skewer of another rider as long as
both bikes still have both wheels on the pavement.

I have. In my first mass start race two riders chased me down for
setting a fast pace at the start and cut across my front wheel so that
one of my spokes opened the rear QR of the second rider while ripping
a spoke out of my wheel. He was riding Simplex hubs. I lost a bit of
skin off my elbow and also needed a new Fiamme rim.

I don't believe this is typical and I still see it as a freak event.

Jobst Brandt

On 24 Feb 2006 15:16:15 -0800, "Chris M" <[email hidden]>

Quoted message said:

In all my years racing and training I can't recall ever seeing a guy
break a spoke from contact of the skewer of another rider as long as
both bikes still have both wheels on the pavement.

I've seen spokes become severely bent and the wheel start to wobble
from that kind of contact.

JT

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Quoted message said:

Andrew F Martin said:

Or hit a pothole/traffic turtle at 40+mph. There's some stresses
going on there, and they don't go away just because a wheel was
stress relieved.

Tilt! Pot holes and other road hazards do not cause spoke breakage.
Wheel loading, other than few crashes, relax spoke tension, not
increase it. Failures in spokes are fatigue failures, not results of
singular overloads.

Does some sort of high stress event make it more likely that a
fatigued spoke will break?

JT

****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

In article <[email hidden]>,

John Forrest Tomlinson said:

Quoted message said:

Andrew F Martin said:

Or hit a pothole/traffic turtle at 40+mph. There's some stresses
going on there, and they don't go away just because a wheel was
stress relieved.

Tilt! Pot holes and other road hazards do not cause spoke breakage.
Wheel loading, other than few crashes, relax spoke tension, not
increase it. Failures in spokes are fatigue failures, not results of
singular overloads.

Does some sort of high stress event make it more likely that a
fatigued spoke will break?

I understand what you are saying. Suppose a spoke has not
been stress relieved. This raises the probability that it
will fail in use; the mechanism being the cyclic unloading
and loading of the spoke as it passes the contact patch.
Fatigue failure is the result of many ( >10^5) cycles.
When a spoke takes a load it becomes less tense. This is
when the fatigue point bends. If one event such as a road
bump that induces a larger than typical unloading is
coincident in time with fatigue failure of the spoke, it
remains but one unloading; it is mere coincidence. Normal
running would have led to fatigue failure without the road
bump. To a spoke a road bump is all in a days work. Note
how large bumps will bend a rim, and never break a spoke.

--
Michael Press

John Forrest Tomlinson said:

Quoted message said:

Andrew F Martin said:

Or hit a pothole/traffic turtle at 40+mph. There's some stresses
going on there, and they don't go away just because a wheel was
stress relieved.

Tilt! Pot holes and other road hazards do not cause spoke breakage.
Wheel loading, other than few crashes, relax spoke tension, not
increase it. Failures in spokes are fatigue failures, not results of
singular overloads.

Does some sort of high stress event make it more likely that a
fatigued spoke will break?

JT

The usual way it works is this: when spokes have their elbow bent into
them, there are residual stresses on certain very small areas of
material left over at the elbow. Those stresses are there even as the
spoke sits unlaced. This is a tension load on the outer part of the
elbow and compression load on the inner. When the wheel is built and
further tension is added to the spokes, the part that had the built-in
tension is now very close to the yield point for the material. If the
wheel is ridden in that state, the spoke is liable to break there, as
metals do when they're loaded cyclically at near enough to their yield
point. This problem can be eliminated by stress relieving the spokes
during the build process after tension has been added. To do this, one
simply temporarily adds enough tension to each spoke to bring the
entire length of each to beyond their yield point. There are different
ways this can be done, some of which probably don't actually work very
well. This takes care of the most common causes of spoke breakage and
virtually all breaking at the elbow.

There are other ways in which spokes can break from fatigue. Some of
them involve similar problems with built-in stresses from bends at the
elbow and the spoke nipple, which can also be corrected by the
wheelbuilder. The other possibility is if spokes are routinely being
completely unloaded - a somewhat inherent problem with 8/9/10s wheels,
especially with light rims, where the left spokes usually have very
little tension, and also a problem with any wheel with not enough
tension for the load. In addition to creating other problems with how
well a wheel works and how durable it is, spokes that are completely
unloaded all the time also experience fatigue that can and does lead to
breakage.

To answer your question, high stress events do technically contribute
to spoke breakage if they completely unload the spokes, or come close
to it, because spokes don't like that. But this is very much a
technicality with regard to wheels that experience that kind of lack of
tension as isolated incidents. And wheels that get completely unloaded
like that all the time are going to die for other reasons.

Quoted message said:

Andrew F Martin said:

Or hit a pothole/traffic turtle at 40+mph. There's some stresses
going on there, and they don't go away just because a wheel was
stress relieved.

Tilt! Pot holes and other road hazards do not cause spoke breakage.
Wheel loading, other than few crashes, relax spoke tension, not
increase it. Failures in spokes are fatigue failures, not results of
singular overloads.

oh dear, the jobstian concept singularity appears again.

1. spoke tension increases under lateral loads.
2. re-application of stress to a fatigue cracked spoke can exceed its
fracture limit and cause failure. that's a basic fundamental of fatigue
failure you should know by now.

Quoted message said:

On that note. If you damage a wheel beyond repair, do not unspoke it
nor throw the spokes away.

if spokes are cracking, throw them away. they've been allowed to
fatigue. unless you think that "stress relief" can magically transform
the stainless steel into a strain aging material that has an endurance
limit.

Quoted message said:

Lay a new rim of the same kind next to the
old and transfer the spokes one at a time to the new rim and true the
wheel. These spokes will most likely outlive a new set.

Jobst Brandt

John Forrest Tomlinson said:

Quoted message said:

Andrew F Martin said:

Or hit a pothole/traffic turtle at 40+mph. There's some stresses
going on there, and they don't go away just because a wheel was
stress relieved.

Tilt! Pot holes and other road hazards do not cause spoke breakage.
Wheel loading, other than few crashes, relax spoke tension, not
increase it. Failures in spokes are fatigue failures, not results of
singular overloads.

Does some sort of high stress event make it more likely that a
fatigued spoke will break?

absolutely. it can raise the stress at the crack tip above the fracture
limit causing sudden failure. strain rate has an influence too.

Quoted message said:

JT

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****************************

Quoted message said:

In all my years racing and training I can't recall ever seeing a guy
break a spoke from contact of the skewer of another rider as long as
both bikes still have both wheels on the pavement.

I guy next to me, had his hub come apart, and the wheel caved in. When
all of this was going on, the skewer shot out and barely missed my face.
Don't ask me what happened, I kept going, but it was the weirdest thing I've
ever seen.

Nate Knutson said:

Quoted message said:

Floyd reportedly broke a spoke in yesterday's stage 4 of the Tour of
California.

"Then, at mile 65, Landis broke a spoke and stopped for a wheel
change."

http://www.velonews.com/race/dom/articles/9535.0.html

I seem to remember another Zipp wheel reportedly breaking a spoke in
pro race within the last year or two, but can't find the reference now.

Don't Zipp know about stress relieving? Or why else might the spoke
break? Do other pro tema's wheels break spokes any more?

The other main reasons why spokes break in 8/9/10s wheels are if they
have bends at the hub or nipple, which isn't a new problem, or when
spokes on the left side get completely unloaded in use all the time,
causing them to break from fatigue
(http://sheldonbrown.com/wheelbuild.html#half-radial). How this might
change with low-spoke count wheels where the left spokes can have a lot
more tension, but also get loaded more heavily because there's fewer
spokes, is something I'm unclear about. (Also, many of those wheels
have radial left spokes anyway, which according to the stance on
Sheldon's page would mostly eliminate the problem.. but I think it's
somewhat contentious whether torque load actually contributes to this
problem all that much.)

There's also the fact that some (I don't really know how many) of these
wheels have spokes with 200+ kgfs of tension, and some (none of the
former group, I think) have al spokes. I'm pretty sure that the crazy
high tension ones don't pose any problems to spoke durability beyond
making internal stresses that should be eliminated anyway much more
likely to cause breakage, but I could be wrong about this. Jobst has
said that the tension in highly tensioned spokes on conventional wheels
is something like a third of their tensile strength. So the question is
whether operating at more like two thirds of their tensile strength
would be okay.

As for aluminum spokes, I'm pretty happy to have not thought about it
very much.

Hope any of this helps... I also have questions about this stuff but
the truth is probably that boutique wheels aren't even designed by
people with clear understandings of any of this

eh??? nate, you can't say that. when a "boutique" wheel designer
eliminates j-bend spokes, it's because they understand that the
fundamental problem of non-axial loading and the fatigue it causes!!!
that individual has done way more homework than the dude that concocts a
"fatigue elimination" theory based on fundamental misconceptions.

Quoted message said:

, which makes figuring
it all out kind of a lonely road.

John Forrest Tomlinson said:

Quoted message said:

Quoted message said:

Or hit a pothole/traffic turtle at 40+mph. There's some stresses
going on there, and they don't go away just because a wheel was
stress relieved.

Quoted message said:

Quoted message said:

Tilt! Pot holes and other road hazards do not cause spoke
breakage. Wheel loading, other than few crashes, relax spoke
tension, not increase it. Failures in spokes are fatigue failures,
not results of singular overloads.

Quoted message said:

Does some sort of high stress event make it more likely that a
fatigued spoke will break?

No, because it will rip a spoke out of the rim before the spoke
yields. You'll have to jab a foreign object into the wheel and kink a
spoke to cause a spoke failure.

Jobst Brandt

Nate Knutson said:

Quoted message said:

Quoted message said:

> Or hit a pothole/traffic turtle at 40+mph. There's some stresses
> going on there, and they don't go away just because a wheel was
> stress relieved.

Quoted message said:

Quoted message said:

Quoted message said:

Tilt! Pot holes and other road hazards do not cause spoke
breakage. Wheel loading, other than few crashes, relax spoke
tension, not increase it. Failures in spokes are fatigue
failures, not results of singular overloads.

Quoted message said:

Quoted message said:

Does some sort of high stress event make it more likely that a
fatigued spoke will break?

Quoted message said:

The usual way it works is this: when spokes have their elbow bent into
them, there are residual stresses on certain very small areas of
material left over at the elbow. Those stresses are there even as the
spoke sits unlaced. This is a tension load on the outer part of the
elbow and compression load on the inner.

You are on the right track as I see it but you got the stresses
switched. When the elbow is bent, tension is on the outside and
compression on the inside. When the bending force is removed,
spring-back reverses these stresses. It doesn't really make any
difference because spoke tension in the wheel adds to the residual
tension and raises it to the fatigue limit stress.

Quoted message said:

When the wheel is built and further tension is added to the spokes,
the part that had the built-in tension is now very close to the
yield point for the material. If the wheel is ridden in that state,
the spoke is liable to break there, as metals do when they're loaded
cyclically at near enough to their yield point. This problem can be
eliminated by stress relieving the spokes during the build process
after tension has been added. To do this, one simply temporarily
adds enough tension to each spoke to bring the entire length of each
to beyond their yield point. There are different ways this can be
done, some of which probably don't actually work very well. This
takes care of the most common causes of spoke breakage and virtually
all breaking at the elbow.

Quoted message said:

There are other ways in which spokes can break from fatigue. Some of
them involve similar problems with built-in stresses from bends at the
elbow and the spoke nipple, which can also be corrected by the
wheelbuilder. The other possibility is if spokes are routinely being
completely unloaded - a somewhat inherent problem with 8/9/10s wheels,
especially with light rims, where the left spokes usually have very
little tension, and also a problem with any wheel with not enough
tension for the load. In addition to creating other problems with how
well a wheel works and how durable it is, spokes that are completely
unloaded all the time also experience fatigue that can and does lead to
breakage.

I don't believe that slackening spokes are more subject to failure
because it is the cyclic stress near the elastic limit that causes
rapid fatigue failure. A slack spoke cannot reach such tension
regardless of position.

Quoted message said:

To answer your question, high stress events do technically contribute
to spoke breakage if they completely unload the spokes, or come close
to it, because spokes don't like that. But this is very much a
technicality with regard to wheels that experience that kind of lack of
tension as isolated incidents. And wheels that get completely unloaded
like that all the time are going to die for other reasons.

If you could explain the mechanism for this I could be convinced, but
as yet I have not heard anyone explain this and I am afraid the more
it gets repeated, the more it will become "boiler plate".

Jobst Brandt

Southern Comfort said:

Quoted message said:

Quoted message said:

Or hit a pothole/traffic turtle at 40+mph. There's some stresses
going on there, and they don't go away just because a wheel was
stress relieved.

Quoted message said:

Quoted message said:

Tilt! Pot holes and other road hazards do not cause spoke
breakage. Wheel loading, other than few crashes, relax spoke
tension, not increase it. Failures in spokes are fatigue failures,
not results of singular overloads.

Quoted message said:

oh dear, the jobstian concept singularity appears again.

Quoted message said:

1. spoke tension increases under lateral loads.

You'll need to show how this 0occurs and how you determined that it
does. I have explained that leaning the bicycle while pedaling in the
standing position, seldom makes the tire contact point with the road
make an excursion farther than the width of the flange spacing of the
front wheel (where the rider weight is). Even when it does, spoke
tension reduction from radial loading is greater than the imagined
increase off axis forces give the wheel. Try this in your own living
room with someone plucking spokes while you lean the bicycle to the
side in typical riding fashion.

Quoted message said:

2. re-application of stress to a fatigue cracked spoke can exceed
its fracture limit and cause failure. that's a basic fundamental of
fatigue failure you should know by now.

Oh! Then these are fatigue failures after all. You7 must have read
about this in "The Bicycle Wheel".

Quoted message said:

Quoted message said:

On that note. If you damage a wheel beyond repair, do not unspoke
it nor throw the spokes away.

Quoted message said:

if spokes are cracking, throw them away. they've been allowed to
fatigue. unless you think that "stress relief" can magically
transform the stainless steel into a strain aging material that has
an endurance limit.

Who said spokes were cracking?

Quoted message said:

Quoted message said:

Lay a new rim of the same kind next to the old and transfer the
spokes one at a time to the new rim and true the wheel. These
spokes will most likely outlive a new set.

Jobst Brandt

Quoted message said:

Nate Knutson said:

Quoted message said:

>> Or hit a pothole/traffic turtle at 40+mph. There's some stresses
>> going on there, and they don't go away just because a wheel was
>> stress relieved.

Quoted message said:

Quoted message said:

> Tilt! Pot holes and other road hazards do not cause spoke
> breakage. Wheel loading, other than few crashes, relax spoke
> tension, not increase it. Failures in spokes are fatigue
> failures, not results of singular overloads.

Quoted message said:

Quoted message said:

Does some sort of high stress event make it more likely that a
fatigued spoke will break?

Quoted message said:

The usual way it works is this: when spokes have their elbow bent into
them, there are residual stresses on certain very small areas of
material left over at the elbow. Those stresses are there even as the
spoke sits unlaced. This is a tension load on the outer part of the
elbow and compression load on the inner.

You are on the right track as I see it but you got the stresses
switched. When the elbow is bent, tension is on the outside and
compression on the inside. When the bending force is removed,
spring-back reverses these stresses. It doesn't really make any
difference because spoke tension in the wheel adds to the residual
tension and raises it to the fatigue limit stress.

Quoted message said:

When the wheel is built and further tension is added to the spokes,
the part that had the built-in tension is now very close to the
yield point for the material. If the wheel is ridden in that state,
the spoke is liable to break there, as metals do when they're loaded
cyclically at near enough to their yield point. This problem can be
eliminated by stress relieving the spokes during the build process
after tension has been added. To do this, one simply temporarily
adds enough tension to each spoke to bring the entire length of each
to beyond their yield point. There are different ways this can be
done, some of which probably don't actually work very well. This
takes care of the most common causes of spoke breakage and virtually
all breaking at the elbow.

Quoted message said:

There are other ways in which spokes can break from fatigue. Some of
them involve similar problems with built-in stresses from bends at the
elbow and the spoke nipple, which can also be corrected by the
wheelbuilder. The other possibility is if spokes are routinely being
completely unloaded - a somewhat inherent problem with 8/9/10s wheels,
especially with light rims, where the left spokes usually have very
little tension, and also a problem with any wheel with not enough
tension for the load. In addition to creating other problems with how
well a wheel works and how durable it is, spokes that are completely
unloaded all the time also experience fatigue that can and does lead to
breakage.

I don't believe that slackening spokes are more subject to failure
because it is the cyclic stress near the elastic limit that causes
rapid fatigue failure. A slack spoke cannot reach such tension
regardless of position.

Quoted message said:

To answer your question, high stress events do technically contribute
to spoke breakage if they completely unload the spokes, or come close
to it, because spokes don't like that. But this is very much a
technicality with regard to wheels that experience that kind of lack of
tension as isolated incidents. And wheels that get completely unloaded
like that all the time are going to die for other reasons.

If you could explain the mechanism for this I could be convinced, but
as yet I have not heard anyone explain this and I am afraid the more
it gets repeated, the more it will become "boiler plate".

Jobst Brandt

My "understanding" of this is pretty much a regurgitation of Sheldon's
page (http://sheldonbrown.com/wheelbuild.html#half-radial), which is
usually something like the most trustworthy, non-hyperbolic reference
for bike stuff there is. To be honest I haven't dealt with enough
broken spokes on 8/9/10 speed wheels to have a feel for whether the
left side spokes actually break more often. If they do, and the idea
that it happens because they commonly get down to very low tensions is
false, then one other explanation might be the fact that the right
spokes on those wheels usually need little or no spoke line correction
at the hub, while the left spokes need a lot, a wheel built without
correcting spoke line would have a tendency to break left but not right
spokes because of it. If this is what's going on then it would also
make sense that the problem would stop if the wheel got rebuilt
half-radial with the left spokes all heads-out.