Re: Spoke stress

Quoted message said:

Carl Fogel said:

[snip]

Quoted message said:

Quoted message said:

That this scenario occurs was demonstrated by spokes that had
poorer fatigue characteristics and were made noticeably more
durable by mechanical stress reliving (momentary overload). Stress
relieving, even on better spoke, material is worth the effort as is
evident from spoke failure reports with today's better spoke
material.

Quoted message said:

Please tell us where we can find actual tests or statistical failure
data that support your claim, as opposed to anecdotes.

The way you say that, I could take that as calling me a liar.

[snip]

Dear Jobst,

Let's say "possibly mistaken" and skip the familiar red herring.

Cheers,

Carl Fogel

Quoted message said:

Others have experimented with mechanical stress relieving and have
made it a part of their routine. As I said, Damon Rinard at Trek
didn't take it on faith, he tested it.

Is there a report on that test available... or even a summary? I'm
interested...

Ron Ruff said:

Quoted message said:

Others have experimented with mechanical stress relieving and have
made it a part of their routine. As I said, Damon Rinard at Trek
didn't take it on faith, he tested it.

Quoted message said:

Is there a report on that test available... or even a summary? I'm
interested...

There probably is documentation, but I suspect it is company private.
I know of it from talking to Damon who described the method and that
Trek stress relieves all their wheels that way. Essentially the rim
is supported on a flat surface while the axle is depressed by a
pneumatic piston that momentarily overloads the down-side while
slackening the up-side spokes. Then the wheel is turned over and the
process repeated. He didn't mention the loads nor the give a detailed
description of the machine and its controller.

Jobst Brandt

On 20 Dec 2006 22:50:32 -0800, "Ron Ruff" <[email hidden]>

Quoted message said:

Quoted message said:

Others have experimented with mechanical stress relieving and have
made it a part of their routine. As I said, Damon Rinard at Trek
didn't take it on faith, he tested it.

Is there a report on that test available... or even a summary? I'm
interested...

Dear Ron,

"As has been mentioned," we could tell you, but then we'd have to kill
you.

The mystery tests of various companies would be nice to see, but they
remain mysteries. Like you, I'm interested. I've emailed a number of
companies and individuals about spoke tests mentioned on their web
sites without ever even receiving a reply.

Unfortunately, nothing about the mystery tests indicates that they
separate bedding and unwinding from stress relief, any more than the
familiar anecdotal evidence does.

That is, if someone ever did perform the enormous amount of practical
testing needed to compare squeezed and unsqueezed spokes and found
that squeezed spokes lasted longer, it still wouldn't show whether it
was due to bedding in, unwinding, stress relief, or a combination of
all three effects.

And yes, purely practical testing would be an enormous undertaking.
The _only_ spoke tests that I know of were performed back in the
1980's for Wheelsmith at Stanford and took something like two months
of continuous, heavily over-loaded testing to break about 80 spokes.

As for spoke-squashing rigs, it would be interesting to see whether
posters on RBT would be willing to accept such wheels without
squeezing the spokes again themselves. Belief in stress relief is
often accompanied by a strong belief that factory wheels are trash.

Cheers,

Carl Fogel

Quoted message said:

I would rather see what you think is incorrect in my posting that the
"[snip]" above replaces. Instead of saying it isn't so, wold you
point out what in that piece you find is contrary to engineering
understanding of materials?

I, too, am interested in this question. More specifically: how is it
possible for there not to be residual stresses in the spoke of a built
wheel, how is it possible for those stresses to not have a negative
effect on fatigue life, and how is it possible not to reduce them with a
significant but brief overload?

Jobst Brandt said:

Trek stress relieves all their wheels that way. Essentially the rim
is supported on a flat surface while the axle is depressed by a
pneumatic piston that momentarily overloads the down-side while
slackening the up-side spokes. Then the wheel is turned over and the
process repeated.

Interesting method. It seems that technique also would take out any
spoke wind-up, assuming all the spokes completely slacken.
--
terry morse - Undiscovered Country Tours - http://www.udctours.com/

Quoted message said:

As for spoke-squashing rigs, it would be interesting to see whether
posters on RBT would be willing to accept such wheels without
squeezing the spokes again themselves. Belief in stress relief is
often accompanied by a strong belief that factory wheels are trash.

Stress relieving is such a simple process that I always do it on wheels
I build myself or buy already built up. Some factory wheels are trash,
others are not.
------------------
Alex

Peter Cole said:

Quoted message said:

I would rather see what you think is incorrect in my posting that the
"[snip]" above replaces. Instead of saying it isn't so, wold you
point out what in that piece you find is contrary to engineering
understanding of materials?

I, too, am interested in this question. More specifically: how is it
possible for there not to be residual stresses in the spoke of a built
wheel, how is it possible for those stresses to not have a negative
effect on fatigue life, and how is it possible not to reduce them with a
significant but brief overload?

you're never /not/ going to have some degree of residual stress, "stress
relieved" or not, on highly cold worked wire. ever. having established
that, you /now/ concentrate on the factors that /can/ be controlled and
which /do/ quantifiably have a positive affect on fatigue life, notably
inclusion content [vacuum de-gas] and surface finish.

Terry Morse said:

Quoted message said:

Trek stress relieves all their wheels that way. Essentially the
rim is supported on a flat surface while the axle is depressed by a
pneumatic piston that momentarily overloads the down-side while
slackening the up-side spokes. Then the wheel is turned over and
the process repeated.

Quoted message said:

Interesting method. It seems that technique also would take out any
spoke wind-up, assuming all the spokes completely slacken.

Properly built wheels have no spoke windup and that is what Holland
Mechanics, a major manufacturer wheel building machines, is intent on
achieving. Spoke windup was such a severe problem on early machines
that it limited the ability to reach high tension, something that was
brought to a head with fewer spokes that requires higher tension. It
was the tension limit, caused by spoke windup, that gave machine built
wheels a bad name, and it has, to a degree, stuck.

SpokePrep was invented to cover for the resulting low tension that
allowed spoke nipples to unscrew with repeated slackening of spokes in
use. With ever fewer spokes, tension had to increase regardless of
SpokePrep, and that focused on preventing spoke twist which interfered
with spoke adjustment.

The problem:

Knowing the spoke thread and the amount of lateral and radial truing
necessary, the required rotation of the spoke nipple can be derived.
However, if the spoke twists, no adjustment takes place when the
nipple is turned the prescribed amount. This resulted in an infinite
repetition of spoke adjustments.

http://www.hollandmechanics.com/

http://www.bmd.nl/index_products.htm

As I mentioned about InterBike, I talked with Holland Mechanics and
BMD about a simple way of preventing spoke twist, the bane of truing
machines, and hope to see a more reliable method implemented soon. At
present robotic pliers reach out below the nipple chuck to clamp the
spoke. That this does not work reliably can be tested by using
pliers.

I think it was from that realization that I was asked by Holland
Mechanics to describe how to prevent windup by a more reliable method,
one that I used in building 24-spoke track wheels with thin spokes,
when 24 was considered low spoke count. Placing the wheel in a sturdy
truing fixture, I pulled the rim laterally toward the spoke to be
adjusted, nearly slackening it and making spoke nipple rotation freer.
With a machine, a pneumatic piston can radially press on the rim to
slacken the spoke in question.

Over the years that I have been building wheels I have heard no
untwisting sounds because I use an over-shoot-and-back-off method to
adjust spokes. Readers of "the Bicycle Wheel" know how to do that as
well, it being mentioned in the book under "Spoke Twist".

Jobst Brandt

Quoted message said:

Terry Morse said:

Quoted message said:

Trek stress relieves all their wheels that way. Essentially the
rim is supported on a flat surface while the axle is depressed by a
pneumatic piston that momentarily overloads the down-side while
slackening the up-side spokes. Then the wheel is turned over and
the process repeated.

Quoted message said:

Interesting method. It seems that technique also would take out any
spoke wind-up, assuming all the spokes completely slacken.

Properly built wheels have no spoke windup and that is what Holland
Mechanics, a major manufacturer wheel building machines, is intent on
achieving. Spoke windup was such a severe problem on early machines
that it limited the ability to reach high tension, something that was
brought to a head with fewer spokes that requires higher tension. It
was the tension limit, caused by spoke windup, that gave machine built
wheels a bad name, and it has, to a degree, stuck.

propagated by whom? the most vitriolic critic of machine build wheels
i've ever seen is your spiteful mistaken self.

Quoted message said:

SpokePrep was invented to cover for the resulting low tension that
allowed spoke nipples to unscrew with repeated slackening of spokes in
use.

er, jobst, you know that we have 10-speed rear wheels now, right? the
shallow dish angle they use, and with which you are clearly unfamiliar,
means the non-drive side spokes can easily be made to go slack. unless
you over-tension the drive side spokes of course, but that cracks rims.
hence we need thread lock. /that/ is why manufacturers of pre-built
wheels, people that have done their homework with extensive testing, use
locking spoke nipples.

Quoted message said:

With ever fewer spokes, tension had to increase regardless of
SpokePrep, and that focused on preventing spoke twist which interfered
with spoke adjustment.

tension does not "have" to increase. slack spokes may be undesirable,
but they are not going to cause a wheel to collapse. and if straight
pull spokes are used, occasional slacking wont even cause elbow bending
fatigue.

Quoted message said:

The problem:

Knowing the spoke thread and the amount of lateral and radial truing
necessary, the required rotation of the spoke nipple can be derived.
However, if the spoke twists, no adjustment takes place when the
nipple is turned the prescribed amount. This resulted in an infinite
repetition of spoke adjustments.

http://www.hollandmechanics.com/

http://www.bmd.nl/index_products.htm

you're assuming they haven't thunk of that.

Quoted message said:

As I mentioned about InterBike, I talked with Holland Mechanics and
BMD about a simple way of preventing spoke twist, the bane of truing
machines, and hope to see a more reliable method implemented soon. At
present robotic pliers reach out below the nipple chuck to clamp the
spoke. That this does not work reliably can be tested by using
pliers.

so you spoke to a guy at a show, but are contending that they paid
attention to you? wow, that's impressive! btw, can you please explain
exactly how the torsional elasticity of a spoke changes with tension?

Quoted message said:

I think it was from that realization that I was asked by Holland
Mechanics to describe how to prevent windup by a more reliable method,
one that I used in building 24-spoke track wheels with thin spokes,
when 24 was considered low spoke count. Placing the wheel in a sturdy
truing fixture, I pulled the rim laterally toward the spoke to be
adjusted, nearly slackening it and making spoke nipple rotation freer.
With a machine, a pneumatic piston can radially press on the rim to
slacken the spoke in question.

otoh, if you know the torsional elasticity of the spoke... oh, wait,
you didn't suggest that, so never mind.

Quoted message said:

Over the years that I have been building wheels I have heard no
untwisting sounds because I use an over-shoot-and-back-off method to
adjust spokes. Readers of "the Bicycle Wheel" know how to do that as
well, it being mentioned in the book under "Spoke Twist".

never miss a sales opportunity!

btw, when is the next [corrected] edition due out jobst? can i
pre-order a copy? i tossed your last edition in disgust when i saw the
extent to which you make fundamental error after fundamental error.
"peer reviewed" - wasn't that the excuse you tried to use in justification?

Jobst Brandt said:

Over the years that I have been building wheels I have heard no
untwisting sounds because I use an over-shoot-and-back-off method to
adjust spokes. Readers of "the Bicycle Wheel" know how to do that as
well, it being mentioned in the book under "Spoke Twist".

I've used the over-shoot-and-back-off method of spoke adjustment for
years (decades), but I've had trouble doing that with very thin
spokes. The amount of wind-up varies from spoke to spoke, and even
varies on the same spoke as it is tensioned. This variability makes
it hard to guess correctly how much to back off each nipple.

I've built thin spoke wheels using both the over-shoot-and-back-off
and the hold-spoke-while-adjusting method. The second method is more
reliable, I never get the charcteristic "ping, ping" of untwisting
spokes after using this method. Not so with over-shoot-and-back-off.
--
terry morse - Undiscovered Country Tours - http://www.udctours.com/

Terry Morse said:

Quoted message said:

Over the years that I have been building wheels I have heard no
untwisting sounds because I use an over-shoot-and-back-off method
to adjust spokes. Readers of "the Bicycle Wheel" know how to do
that as well, it being mentioned in the book under "Spoke Twist".

Quoted message said:

I've used the over-shoot-and-back-off method of spoke adjustment for
years (decades), but I've had trouble doing that with very thin
spokes. The amount of wind-up varies from spoke to spoke, and even
varies on the same spoke as it is tensioned. This variability makes
it hard to guess correctly how much to back off each nipple.

Quoted message said:

I've built thin spoke wheels using both the over-shoot-and-back-off
and the hold-spoke-while-adjusting method. The second method is more
reliable, I never get the characteristic "ping, ping" of untwisting
spokes after using this method. Not so with over-shoot-and-back-off.

There's a fine sense way of assessing windup by feeling the torque
when tightening and loosening a tight spoke. (Only the final
tightening counts.) A tight spoke will begin to twist and then break
loose when it has built up enough torque to make the thread move.
This can be felt and it is different for tightening and loosening
because one is uphill, so to speak, and the other is down the thread
ramp.

This break loose point is difficult to feel if the spoke nipple to rim
interface is not well lubricated. I suspect most people do not pay
attention to that aspect or we wouldn't have spoke wrenches that are
in essence slotted four sided socket wrenches. With my hardened
steel, slotted spoke wrenches, I can twist off any spoke I have met
yet do not round off spoke nipples. That dry cork sound I often hear
when I see wheels being built in bicycle shops is a sure sign that the
brass spoke nipple is galling.

Jobst Brandt

Terry Morse said:

I've used the over-shoot-and-back-off method of spoke adjustment for
years (decades), but I've had trouble doing that with very thin
spokes. The amount of wind-up varies from spoke to spoke, and even
varies on the same spoke as it is tensioned. This variability makes
it hard to guess correctly how much to back off each nipple.

I've built thin spoke wheels using both the over-shoot-and-back-off
and the hold-spoke-while-adjusting method. The second method is more
reliable, I never get the charcteristic "ping, ping" of untwisting
spokes after using this method. Not so with over-shoot-and-back-off.

Terry,

Besides the "hold-spoke-while-adjusting method" you mention, the
variability can be eliminated by marking the spokes, as described here:

http://groups.google.com/group/rec.bicycles.tech/msg/6f4b972918e1096f

Even after building several wheels and developing a "feel" for windup,
I still find it helpful to do this. The only cost is the ~90 seconds it
takes to apply the marks. I've never tried the
"hold-spoke-while-adjusting method", but I suspect it requires more
work than simply marking them.

Best,
Stephen Greenwood

Stephen Greenwood said:

Quoted message said:

I've used the over-shoot-and-back-off method of spoke adjustment
for years (decades), but I've had trouble doing that with very thin
spokes. The amount of wind-up varies from spoke to spoke, and even
varies on the same spoke as it is tensioned. This variability
makes it hard to guess correctly how much to back off each nipple.

Quoted message said:

Quoted message said:

I've built thin spoke wheels using both the over-shoot-and-back-off
and the hold-spoke-while-adjusting method. The second method is
more reliable, I never get the characteristic "ping, ping" of
untwisting spokes after using this method. Not so with
over-shoot-and-back-off.

Quoted message said:

Besides the "hold-spoke-while-adjusting method" you mention, the
variability can be eliminated by marking the spokes, as described
here:

http://groups.google.com/group/rec.bicycles.tech/msg/6f4b972918e1096f

Quoted message said:

Even after building several wheels and developing a "feel" for
windup, I still find it helpful to do this. The only cost is the
~90 seconds it takes to apply the marks. I've never tried the
"hold-spoke-while-adjusting method", but I suspect it requires more
work than simply marking them.

I also used the marking method and that is how I discovered how poorly
holding spokes with pliers works. As I said, I do fine with backing
off. The test of the method is to coast standing on one pedal while
leaning far to either side. That puts a smooth side load on the wheel
that nearly slacken the spokes.

Jobst Brandt

jim beam said:

Quoted message said:

Spoke windup was such a severe problem on early machines
that it limited the ability to reach high tension, something that was
brought to a head with fewer spokes that requires higher tension. It
was the tension limit, caused by spoke windup, that gave machine built
wheels a bad name, and it has, to a degree, stuck.

btw, can you please explain
exactly how the torsional elasticity of a spoke changes with tension?

I think it's clear that spoke windup increases with tension due to
static friction between spoke and nipple, and not to a change in the
properties of the spoke itself. Is the latter what you are suggesting?

Chalo

Stephen Greenwood said:

Besides the "hold-spoke-while-adjusting method" you mention, the
variability can be eliminated by marking the spokes, as described here:

http://groups.google.com/group/rec.bicycles.tech/msg/6f4b972918e1096f

Even after building several wheels and developing a "feel" for windup,
I still find it helpful to do this. The only cost is the ~90 seconds it
takes to apply the marks. I've never tried the
"hold-spoke-while-adjusting method", but I suspect it requires more
work than simply marking them.

Thanks, I haven't tried the "mark the spokes" method in quite a
while. Maybe I'll try that on my mext wheel.

For holding the spokes, I have purchased the Twist Resist tool:

http://www.sheldonbrown.com/harris/tools/wheel.html

It's fairly easy to use and does the job.

Chalo said:

jim beam said:

Quoted message said:

Spoke windup was such a severe problem on early machines
that it limited the ability to reach high tension, something that was
brought to a head with fewer spokes that requires higher tension. It
was the tension limit, caused by spoke windup, that gave machine built
wheels a bad name, and it has, to a degree, stuck.

btw, can you please explain
exactly how the torsional elasticity of a spoke changes with tension?

I think it's clear that spoke windup increases with tension due to
static friction between spoke and nipple, and not to a change in the
properties of the spoke itself. Is the latter what you are suggesting?

Chalo

you got it right, the spoke properties don't change, just the friction.