Breaking Spokes

Mark South said:

"Mark South" <[email hidden]> wrote in message
news:[email hidden]...

I'm sorry, I have made a mistake or two in the following, which I attribute to
my inability to leave numbers alone no matter how short of sleep I am.

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"jim beam" <[email hidden]> wrote in message
news:[email hidden]...

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[email hidden] wrote:

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>Now, tension the spoke to the yield stress and relax it again. I
>think you'll see a perfectly straight spoke with no residual stress.
>If that is not stress relieving, then you may have abetter word for
>it. Let me know what you find.

well, for the metallurgical definition of stress relief, that would
require between 1% & 3% strain, and even then, that would typically be
done immediately after initial deformation to prevent any possible aging
effects. on a 296mm spoke, if we're conservative, 1% means 3mm
elongation making it unusable for its originally intended purpose.

But the lower end of that limit quite plausible, right? Fully tensioned

spokes

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do exhibit loaded elongations of around 1% and so the stress-relief procedure
described in Jobst's book is taking the spokes to about 1.5% or 2% strain,
clearly within your specified range.

I overestimated, sorry. That should have been:

But approaching the lower end of that limit is quite plausible, right?
Fully tensioned spokes do exhibit loaded elongations approaching 1% and
so the stress-relief procedure described in Jobst's book is taking the
spokes to in the region of 1% strain, close to your specified range.

there's elastic & plastic strain. metallurgical stress relief is only
achieved in the 1-3% /plastic/ strain region. it's easy to get elastic
spoke elongations in the 1mm range, but that's only ~1/3 of 1% but
again, it needs to be _plastic_ strain to achieve relief.

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Regarding aging effects, these can be very slow for stainless steels. Are you
sure they are important in this application for such high purity stainless
steels as DT (for example) are using?

That question stands.

i don't believe it's important to us as consumers. i just mention it
because in the factory, to make a difference in reducing residual stress
after a drawing operation, the second stress relief drawing needs to
take place pretty much immediately. otherwise aging can reduce
effectiveness. depends on alloy.

Old Crow or was it Wild Turkey said:

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So? What is it that is unclear about why these spokes fail so
rapidly and why stress relieving reduces their failure rate as you
see it?

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I don't think your version of "stress relief" brings any
metallurgical change to the spokes, but it definitely builds a
stronger more evenly tensioned wheel. See below for my experiment
last summer.

I don't see your experiment below or are you referring to the URL with
wreck.bike exchange?

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As explained before, one reason for failure of these spokes is their
"dirty" steels. Another is the use of chrome plating. Chrome is
brittle and cracks when the spokes get bent during build. These
cracks are /classic/ fatigue initiators.

Oh, you mean like anodizing on aluminum rims? Actually the old spokes
I listed were not chromed except Berg. Their durability increase was
what led me to stress relief.

I think you are missing a logical point of why spokes fail where they
do. They break at the ends for good reasons. Thread failures are
probably the best place to look. For a spoke to fail in fatigue it
must be operating (cyclic loading) near its yield stress. Since the
tension load on a spoke is far below yield it cannot be the cause,
there must be an additional stress to cause a failure. That stress is
a residual stress from manufacturing and installation. DT as well as
other spokes fail in the threads but if they are stress relieved,
their threads do not fail.

By overloading a spoke temporarily, high stress points must yield so
that when the overload is relaxed, the peak stress becomes lower than
it was. This margin is what makes spokes last longer when stress
relieved. That does not mean all residual stress is removed but the
highest stress is reduced and that is enough to reduce failures.

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Yes, there are now several brands that work well. But their long life
is not the product of "stress relief"; it's the fact that in the 70's,
it became economic to mass produce vacuum degassed steels. Ultra-clean
materials like this are substantially more fatigue resistant because
this process virtually eliminates inclusions, thereby removing a
significant source of fatigue initiation.

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Oh? So how do you explain the reports of repeated failures in wheels
with these spokes, ones built by people who, as you, don't believe
that stress relief is useful or don't know about it.

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Which brand of spokes? The people I've asked for info on which brand of
spoke they've been breaking here on r.b.t. either don't seem to know or
will only admit to pre-built wheels which usually use no-name cheapo
stuff. The broken d.t.'s i have are all victims of chain gouge, so i
don't think they're much of a data point. And when spokes /do/ break,
the wheels usually get rebuilt with high quality after market
replacements, and miraculously, their problems seem to disappear!
coincidence?

No dice. People have failures with DT and Sapim spoke and have
reported about that here. I have had a DT spoke fail near the rim
where I had gotten a hardwood stick in the front wheel that cause an
endo and a kink that was visible but had no scratch on it. I thought
nothing of it before it broke because the spoke was essentially
straight to the eye. It obviously had residual stress or it would not
have broken in fatigue a few thousand miles later.

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How about an experiment? One that I have done. I take it that you
have access to materials testing equipment from what you write.
Take a spoke and manually give it some kinks with as small a radius
as you can. Tension that spoke to customary service tension in a
tensile tester using a simulated 3mm flange hole and holder for a
spoke nipple. I think you'll notice that when relaxed again, the
spoke will still have kinks,

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Agreed - I can repeat this experiment if you like. Probably won't
have time to do it for several weeks, but it's easily done.

I'm sure you can comment on it even if you haven't performed it yet.
Do you believe the results would be as I described above? If so how
do you account for the spoke being straight after being stressed to
yield? Do you agree that his removes residual stress? For instance,
if you bend a spoke and get only partial spring back, do you agree
that this shows residual stress where the outer fibers went beyond
yield while the inner ones that did not and try to return to the
original shape while the outer ones resist. Is that not residual
stress, and if so why do you believe it is not additive to a
subsequent tensile load on the installed spoke?

That is what this experiment is intended to demonstrate. I have
inadvertently done this when I charted the stress strain curves for
"the Bicycle Wheel" in which less than perfectly straight spokes became
straight from stretching them beyond yield.

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kinks that in service would lead to fatigue failure.

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Not necessarily more so than a spoke that's been bent to "correct the
line" or a spoke that's crossing another, particularly if that crossing
is closer to the hub than normal like 2x on a 32 spoke wheel. Depends
on the extent of the kink doesn't it!

I'm sure you can come up with a spoke lacing that is more damaging
than conventional cross patterns. However, we have not seen failures
in common interleaved spoke lacings. I have never seen a failure at a
crossing point so let's drop that one. We have seen many failures at
the elbows, heads popping off, and thread failures as well as mid
spoke failures from smooth kinks, ones that had no knick or gouge.

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Now, tension the spoke to the yield stress and relax it again. I
think you'll see a perfectly straight spoke with no residual stress.
If that is not stress relieving, then you may have abetter word for
it. Let me know what you find.

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Well, for the metallurgical definition of stress relief, that would
require between 1% & 3% strain, and even then, that would typically
be done immediately after initial deformation to prevent any
possible aging effects. On a 296mm spoke, if we're conservative, 1%
means 3mm elongation making it unusable for its originally intended
purpose. Being as we're not getting strain of that magnitude, you
can't contend that there's true metallurgical stress relief in a
wheel build.

Oh but yes. As I mentioned, for a fatigue failure to occur requires
high stress, stress that spoke tension alone does cannot cause.
Spokes fail. Ergo, there is high stress. Overloading a spoke to
relieve that stress causes local yield because the stress is high.

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A traditional steel for example may have half the fatigue limit in the
transverse axis of a rolled sheet compared to its longitudinal axis.
The same alloy composition, but vacuum degassed, may have very similar
fatigue limits in both orientations. When first seen, the observation
of this effect sparked a hunt for explanation. Electron microscopy
subsequently confirmed fatigue initiation at tiny inclusions previously
thought to be insignificantly small.

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So what does this have to do with stress relieving or not?

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I'm trying to tell you /why/ modern spokes have such good fatigue
characteristics!!!

We are talking about failures, not how good spokes are. Besides, it is
documented that the good spokes fail.

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> As I have described here often, spoke wire must be ductile enough
> to withstand cold forming yet retain a sufficiently high yield
> strength to resist fatigue failures at normal spoke loadings.
> This had not been so before DT spokes so there is where you
> should look for the answer. Redaelli, Berg, and Prym spokes also
> did not survive long even with stress relieving although it
> extended their service life.

--- no response

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I see you have no comment on the high ductility and high tensile
strength of DT spoke wire.

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What's to comment? You're the guy that was telling me a while back that
d.t. spokes were fully hard. You didn't respond to links showing the
tensile strength differences between 2.0 straight gauge, 2.0/1.8/2.0
butted and 2.0/1.5/2.0 butted - which are directly attributable to
continued work hardening.

You're the one who did not believe that the ductility shown in the
stress strain curve of the DT spoke that stretched horizontally right
off the chart was not real and that this showed strain hardening. As I
pointed out, you were assuming there was a significant reduction in
cross section from this stretching but for a 300mm long spoke a few
0.1mm does not make a significant change in cross section. The spokes
were not necking locally.

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http://www.google.com/groups?selm=P_r7c.13091%24R46.8853%40newssvr27.news.prodigy.com&output=gplain

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What causes failures is well known. It's what alleviates them that
seems to be the issue here. All that "stress relief" achieves is a
wheel that is fully bedded in before riding. Spokes do not
therefore loosen and others do not therefore carry disproportionate
load. In that respect, the practice referred to as "stress relief"
is a good thing, and thoroughly to be commended. But the business
of fatigue mitigation itself is achieved in the spoke manufacturers
factory, not the wheel builders bench.

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"Well known"? From what you just said, it seems not to be.

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The causes of fatigue are quite well known to metallurgists & materials
engineers. There's tons of stuff about that on the web.

You seem to attribute durability to "bedding in" rather than stress
relief. I propose there is no bedding in after a spoke is tensioned,
the aluminum having yielded or a point where contact area is large
enough to sustain the load. If you unspoke a stress relieved wheel
and one whose spokes have not been loaded by this process, you will
find no visible difference n the dimples made by their spokes although
there is a minuscule change. This is not what prevents spoke failures
and especially not on the threaded end of spokes.

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Bedding in is already complete when spokes are tensioned

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I absolutely disagree. My hefty #210 hindquarters most definitely are
able to untrue a wheel that has not been properly bedded in. Quickly
too. That's where the benefits of the "stress relief" wheel build
process are most apparent.

Oops. What does your weight have to do with "bedding in?" I assume
you are aware that spoke tension does not increase from loading the
wheel. Driving torque causes minimal almost imperceptible increases
and decreases as does braking. However, sitting on the bicycle does
not bed in spokes.

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And even if it weren't, subsequent bedding in from use cannot relax
the tension of a spoke, the change in length being insignificant
compared to spoke elastic stretch from tensioning.

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This is not my experience. Last summer, I /did/ build a wheel,
deliberately without "stress relief". It was evenly tensioned and
perfectly true before leaving the house. I took care to ensure no spoke
had any twist by marking them on one side before assembly so any torque
could easily be seen. It did not "ping" while riding. It was ~6mm out
of true after riding around just one block and some of the spokes were
almost completely slack. Clearly there was measurable yielding of
/something/. As I think we both agree that spokes are loaded to less
than a third of their yield, it had to be something else - yielding of
soft aluminum hub holes & rim holes. Hence the need to /properly/ bed
wheels in.

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However, even if it did, your model of overloaded spokes cannot
explain the failure of left side spokes in rear wheels that have as
little as half the tension of those on the right.

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Why not? If it means the spokes get higher cyclic load limits, i.e. the
difference between the maximum & minimum loads, or even /negative/
loads, I don't see any disparity at all! I have examples of spoke
failures where the elbows have fatigued from both the inside out, /and/
outside in! Clearly in this situation, poor tension is a contributor.

How can a lowly tensioned spoke have higher cyclic loads. It can only
go from zero to the low tension of the left side that is often 1/2 or
less that of the right side of a rear wheel. Cyclic load is
irrelevant to fatigue if it is a tiny fraction of the yield stress.

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Beyond these considerations, high spoke tension is generally
in the range of 1/3 the yield stress of a spoke.

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Which just happens to be about the same stress level we commonly see for
fatigue limits [_not_ to be confused with an endurance limits]. Funny
coincidence that.

Fatigue limit

Definition: The maximum value of the applied alternating stress which
a test piece can stand indefinitely.

Endurance limit

Definition: The maximum value of the applied alternating stress which
a test piece can stand indefinitely. Rigid, elastic, low damping
materials such as thermosetting plastics and some crystalline
thermoplastics do not exhibit an endurance limit. Also known as
FATIGUE LIMIT.

I think you are quibbling. This is not about other materials but
about steel spokes.

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Would you explain your understanding of spoke failure in this respect?

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The explanation of "local yielding" you've presented as theory on
how to eliminate fatigue is unfortunately built on some gross
misconceptions. You assert that the steel in spokes exhibits the
same properties as mild steel, i.e. the exhibition of yield and
deformation without work hardening as a method of reducing residual
stress.

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Where do you find that "unfortunate" scenario? I haven't proposed
anything of the sort. I see a straw man raising his head. Where is
Ray Bolger when we need him. He's probably out there on a yellow
brick road commiserating heart warmingly with a tin man.

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I don't have your book in front of me, but you show a stress/strain
graph for mild steel, i.e. one that exhibits strain aging, then
IIRC, go on to discuss yielding without work hardening. If you knew
the distinction between a material that exhibits strain aging, mild
steel, and one that doesn't, stainless steel, you wouldn't have made
that error.

I don't know what you are getting at. The stress strain curves for

jim beam <[email hidden]> wrote in message

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there's elastic & plastic strain. metallurgical stress relief is only
achieved in the 1-3% /plastic/ strain region.

Significant stress relief occurs before 1% applied total strain. All
that is required for stress relief is that under load the stress range
over the spoke cross section is made smaller. Since stress will
unloaded evenly (elastically), this smaller stress range is retained
and the residual stresses are relaxed. Yes you do need some plastic
strain, since the spoke will load evenly until part of it yields.
Since some of the spoke has tensile residual stress, a significant
portion of the spoke cross-section will have some plastic strain by
the time the applied stress equals the yield strength, which happens
well under 1% strain for these steels.

Aluminum plate is stretched to 1-3% plastic strain to achieve a
greater degree of stress relief than you can get at lower levels and
to stress relieve in the transverse direction at the same time.
However, significant relief occurs much earlier. In the below paper
recently published by Alcoa, see Figure 5. Although simplified, it
illustrates the concept. Curve "A" reaches the yield strength before
0.3% strain. By 0.6% strain, the whole part has yielded. No further
stress relief occurs with further stretching. In reality, materials
are not perfectly plastic, so further stress relief does occur for
larder strains. However, the majority occurs before 1% strain.

(Don't let the title fool you. Microstructural effects, etc, are what
limit the stress relief to something like 90-95% relief instead of
100%. It has little bearing on stress relief in spokes, which is not
trying for 100% relief).
Title:A simplified analysis of the effect of microstructure gradient
on the stress relief of aluminum plates and extrusions Author:Karabin,
ME ; Barlat, F ; Becker, R Institution:Alcoa Tech Ctr,
Journal:INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES; SEP 2003; v.45,
no.9, p.1483-1503

Mike Prime

Rick Warner said:

If they lasted only 500 miles there is a problem, either in materials
or technique. I built a set of 36 spoke wheels this winter.

he brings up a good point, tho. is your average buyer (who does not want to
build their own wheels) better buying a prebuilt wheelset or one from an
LBS with an essentially unknown builder? not everyone can or will go out
and find the "best builder" who may or may not be. prebuilt wheels will
(presumably) be consistent and better than N% of shop built wheels ..
and you'll have a major brand standing behind them. how high N is is a
very good question.

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Took me
an evening. Have almost 1000 miles, mostly 'loaded' (e.g., carrying
panniers filled with stuff). Still true as the night I built them,
not a complaint from the spokes.

i've built 4 pairs of wheels now and i'm very glad to have the experience.
in fact i've built all but one pair of the wheels i'm currently using.
there are, however, a lot of people who should probably not be building
their own wheels. or cooking their own food for that matter.

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Wait until you pop a spoke on the Ksyrium's. If you are not near a
major city, expect to wait a while if you want one of those fancy
spokes as a replacement.

yea .. i have a pair of campagnolo shamals that it's horribly easy to get
parts for (you can get a 6 spoke mini-kit easily and the tool to use it at
sears). the hubs are essentially campag record and the manual has a nice
breakdown guide. this complaint is greatly overstated for at least some
brands.
--
david reuteler
[email hidden]

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Old Crow or was it Wild Turkey said:

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So? What is it that is unclear about why these spokes fail so
rapidly and why stress relieving reduces their failure rate as you
see it?

Quoted message said:

I don't think your version of "stress relief" brings any
metallurgical change to the spokes, but it definitely builds a
stronger more evenly tensioned wheel. See below for my experiment
last summer.

I don't see your experiment below or are you referring to the URL with
wreck.bike exchange?

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As explained before, one reason for failure of these spokes is their
"dirty" steels. Another is the use of chrome plating. Chrome is
brittle and cracks when the spokes get bent during build. These
cracks are /classic/ fatigue initiators.

Oh, you mean like anodizing on aluminum rims?

yes, like anodizing on rims. but if we don't see rim fatigue lines
actually following cracks in the anodizing, then it's not the source of
failure! exercise proper analysis of your failures.

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Actually the old spokes
I listed were not chromed except Berg. Their durability increase was
what led me to stress relief.

I think you are missing a logical point of why spokes fail where they
do. They break at the ends for good reasons. Thread failures are
probably the best place to look. For a spoke to fail in fatigue it
must be operating (cyclic loading) near its yield stress.

rubbish. fatigue can occur /well/ below that.

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Since the
tension load on a spoke is far below yield it cannot be the cause,
there must be an additional stress to cause a failure.

see above. and look at any s-n curve. note the point at which failures
are still occurring. even a mild steel endurance limit is only about
50% of yield.

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That stress is
a residual stress from manufacturing and installation. DT as well as
other spokes fail in the threads but if they are stress relieved,
their threads do not fail.

so why do the manufacturers bother to roll high-radius threads into them
then? have you ever looked at one of these threads under a magnifier?

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By overloading a spoke temporarily, high stress points must yield so
that when the overload is relaxed, the peak stress becomes lower than
it was. This margin is what makes spokes last longer when stress
relieved. That does not mean all residual stress is removed but the
highest stress is reduced and that is enough to reduce failures.

so where do things like miner's linear cumulative damage rule come from
- the life of a component being a function of the number of cycles at
each level of stress?

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>Yes, there are now several brands that work well. But their long life
>is not the product of "stress relief"; it's the fact that in the 70's,
>it became economic to mass produce vacuum degassed steels. Ultra-clean
>materials like this are substantially more fatigue resistant because
>this process virtually eliminates inclusions, thereby removing a
>significant source of fatigue initiation.

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Oh? So how do you explain the reports of repeated failures in wheels
with these spokes, ones built by people who, as you, don't believe
that stress relief is useful or don't know about it.

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Which brand of spokes? The people I've asked for info on which brand of
spoke they've been breaking here on r.b.t. either don't seem to know or
will only admit to pre-built wheels which usually use no-name cheapo
stuff. The broken d.t.'s i have are all victims of chain gouge, so i
don't think they're much of a data point. And when spokes /do/ break,
the wheels usually get rebuilt with high quality after market
replacements, and miraculously, their problems seem to disappear!
coincidence?

No dice. People have failures with DT and Sapim spoke and have
reported about that here.

well, the only sapim failure i can see in a quick google search is a guy
with a powertap hub, but with its huge flanges causing the spoke angles
at the rim to be way outside normal spec, i think we can safely
attribute failure to that rather than failure of the builder to "stress
relieve".

besides which, /reducing/ fatigue is not /eliminating/ fatigue. /every/
stainless spoke will fail at some point - it has no endurance limit.

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I have had a DT spoke fail near the rim
where I had gotten a hardwood stick in the front wheel that cause an
endo and a kink that was visible but had no scratch on it. I thought
nothing of it before it broke because the spoke was essentially
straight to the eye. It obviously had residual stress or it would not
have broken in fatigue a few thousand miles later.

this gets more & more interesting. what this translates to is: "i've
never had a spoke failure in my 300,000 mile wheels. apart from the
ones that i've replaced because they broke."

no, it's not "obvious" that it's residual stress. assigning a failure
mode without proper analysis is like you assigning all rim cracking to
anodizing.

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How about an experiment? One that I have done. I take it that you
have access to materials testing equipment from what you write.
Take a spoke and manually give it some kinks with as small a radius
as you can. Tension that spoke to customary service tension in a
tensile tester using a simulated 3mm flange hole and holder for a
spoke nipple. I think you'll notice that when relaxed again, the
spoke will still have kinks,

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Agreed - I can repeat this experiment if you like. Probably won't
have time to do it for several weeks, but it's easily done.

I'm sure you can comment on it even if you haven't performed it yet.
Do you believe the results would be as I described above?

yes, of course!

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If so how
do you account for the spoke being straight after being stressed to
yield?

er, because it's yielded???

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Do you agree that his removes residual stress?

depends on the degree of yielding, and the behavior of the material! it
could introduce residual stress too! just like "correcting the spoke
line" could introduce residual stress come to that.

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For instance,
if you bend a spoke and get only partial spring back, do you agree
that this shows residual stress where the outer fibers went beyond
yield while the inner ones that did not and try to return to the
original shape while the outer ones resist. Is that not residual
stress, and if so why do you believe it is not additive to a
subsequent tensile load on the installed spoke?

it can be additive. but by that argument, again, "correcting the spoke
line" is more likely to cause harm than good. your advice is
contradictatory. the fact is, we're not dealing with a lab sample here,
we're dealing with a highly worked wire with a multitude of surface
defects, and an uncertain operating environment. the reason real world
production focuses on surface quality in a fatigue environment is that
it's the single most prevalent cause of fatigue failure after
incompetent design. then come factors like material quality, corrosion
and damage in service. then you start getting into the esoteric stuff.
a quick manual squeeze on a spoke being sufficient to exert enough
stress to yield the wire is not an assumption you can make. it's
certainly not one i'd care to propose to my old theory of deformation
professor and keep a straight face.

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That is what this experiment is intended to demonstrate. I have
inadvertently done this when I charted the stress strain curves for
"the Bicycle Wheel" in which less than perfectly straight spokes became
straight from stretching them beyond yield.

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kinks that in service would lead to fatigue failure.

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Not necessarily more so than a spoke that's been bent to "correct the
line" or a spoke that's crossing another, particularly if that crossing
is closer to the hub than normal like 2x on a 32 spoke wheel. Depends
on the extent of the kink doesn't it!

I'm sure you can come up with a spoke lacing that is more damaging
than conventional cross patterns. However, we have not seen failures
in common interleaved spoke lacings. I have never seen a failure at a
crossing point so let's drop that one.

no. the crossing is causing the spokes to bend and therefore be held in
a position of elastic strain at that bend point. that has the same
effect as a residual stress. do the math on how much strain is exerted
at that point because of the bend, then tell me it's insignificant
compared to the degree of residual stress you believe to be present in a
good quality spoke.

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We have seen many failures at
the elbows, heads popping off, and thread failures as well as mid
spoke failures from smooth kinks, ones that had no knick or gouge.

proper analysis please. "no damage" by what definition? did you use a
magnifier?

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Now, tension the spoke to the yield stress and relax it again. I
think you'll see a perfectly straight spoke with no residual stress.
If that is not stress relieving, then you may have abetter word for
it. Let me know what you find.

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Well, for the metallurgical definition of stress relief, that would
require between 1% & 3% strain, and even then, that would typically
be done immediately after initial deformation to prevent any
possible aging effects. On a 296mm spoke, if we're conservative, 1%
means 3mm elongation making it unusable for its originally intended
purpose. Being as we're not getting strain of that magnitude, you
can't contend that there's true metallurgical stress relief in a
wheel build.

Oh but yes. As I mentioned, for a fatigue failure to occur requires
high stress,

no. look at any s/n curve.

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stress that spoke tension alone does cannot cause.
Spokes fail. Ergo, there is high stress.

no. see above. spokes fail, ergo they are made of a material without
an endurance limit, subject to manufacturing variance and an
inconsistent operating environment.

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Overloading a spoke to
relieve that stress causes local yield because the stress is high.

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>A traditional steel for example may have half the fatigue limit in the
>transverse axis of a rolled sheet compared to its longitudinal axis.
>The same alloy composition, but vacuum degassed, may have very similar
>fatigue limits in both orientations. When first seen, the observation
>of this effect sparked a hunt for explanation. Electron microscopy
>subsequently confirmed fatigue initiation at tiny inclusions previously
>thought to be insignificantly small.

Quoted message said:

Quoted message said:

So what does this have to do with stress relieving or not?

Quoted message said:

I'm trying to tell you /why/ modern spokes have such good fatigue
characteristics!!!

We are talking about failures, not how good spokes are. Besides, it is
documented that the good spokes fail.

well that's news! firstly, yes, good spokes fail, but not as readily as
bad spokes!!! secondly, you keep repeating that your wheels are over
300,000 miles "without spoke failures" and that "stress relief"
eliminates fatigue. isn't that inconsistent?

Quoted message said:

Quoted message said:

Quoted message said:

>>As I have described here often, spoke wire must be ductile enough
>>to withstand cold forming yet retain a sufficiently high yield
>>strength to resist fatigue failures at normal spoke loadings.
>>This had not been so before DT spokes so there is where you
>>should look for the answer. Redaelli, Berg, and Prym spokes also
>>did not survive long even with stress relieving although it
>>extended their service life.

Mike Prime said:

jim beam <[email hidden]> wrote in message

Quoted message said:

there's elastic & plastic strain. metallurgical stress relief is only
achieved in the 1-3% /plastic/ strain region.

Significant stress relief occurs before 1% applied total strain. All
that is required for stress relief is that under load the stress range
over the spoke cross section is made smaller. Since stress will
unloaded evenly (elastically), this smaller stress range is retained
and the residual stresses are relaxed. Yes you do need some plastic
strain, since the spoke will load evenly until part of it yields.
Since some of the spoke has tensile residual stress, a significant
portion of the spoke cross-section will have some plastic strain by
the time the applied stress equals the yield strength, which happens
well under 1% strain for these steels.

ok, makes sense.

Quoted message said:

Aluminum plate is stretched to 1-3% plastic strain to achieve a
greater degree of stress relief than you can get at lower levels and
to stress relieve in the transverse direction at the same time.
However, significant relief occurs much earlier. In the below paper
recently published by Alcoa, see Figure 5. Although simplified, it
illustrates the concept. Curve "A" reaches the yield strength before
0.3% strain. By 0.6% strain, the whole part has yielded. No further
stress relief occurs with further stretching. In reality, materials
are not perfectly plastic, so further stress relief does occur for
larder strains. However, the majority occurs before 1% strain.

(Don't let the title fool you. Microstructural effects, etc, are what
limit the stress relief to something like 90-95% relief instead of
100%. It has little bearing on stress relief in spokes, which is not
trying for 100% relief).
Title:A simplified analysis of the effect of microstructure gradient
on the stress relief of aluminum plates and extrusions Author:Karabin,
ME ; Barlat, F ; Becker, R Institution:Alcoa Tech Ctr,
Journal:INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES; SEP 2003; v.45,
no.9, p.1483-1503

Mike Prime

i don't work in the materials biz any more, so i don't have ready access
to this paper - would like to read it tho.

what you say sounds logical. the percentages i quoted were from one of
my old textbooks for drawn steel wires & tubes. can you recommend a
text that might be useful for further reading on highly worked stainless
wires? i was under the impression that at high dislocation densities,
their strain fields tended to interact to the point where they had the
lattice effectively "locked up" with continued work only adding to this
situation, not alleviating it. wouldn't this be the case here?

great to hear from you mike!

jb

RWM said:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Roger Zoul said:

With a 36 spoke wheel you would not have to worry about walking home

even if you did break a spoke. They will roll along quite nicely till
you can get a chance for a replacement. In the past I have ridden
over 30 miles with a broken spoke on my 36 spoke hub, screwed in a
replacement spoke and not had to mess around with retrueing.

Not true. I ruined two 36 spoke rims by riding them home.

I have ridden a 32 spoke front wheel with a broken spoke on 2 occasions,
each with no long-term damage. Each post-break ride, however, were not
terribly long. They were each in the neighborhood of 10 miles.

--
Greg Estep

Tim McNamara said:

Quoted message said:

You'd need to go with a different rim, perhaps a
Torelli Master which is similar to an MA2.

I think the Master is a bit more of a racing rim than the MA2. It is
rated at 435g rather than the 490g or so for the MA2. That is if I
remember correctly. That said, I do like the Master.

http://www.torelli.com/home.html?http://www.torelli.com/parts/wheels.html&1
Master. 435 grams. A good all-round racing and training rim available in
32 and 36 hole. Silver $43.90.

Ukai used to make a MA2-like rim. It was the model "20A." I don't know
of a source. They are double-eyeletted, about 19-20 mm wide, and weigh
about 490g. I believe they are box section. They are not machined.
There is anodizing, but it is very thin and is easily penetrated with
ohm-meter probes. JB has stated that a very thin layer is unlikely to
cause crack initiation problems like thick anodizing does.

David Reuteler said:

...
i've built 4 pairs of wheels now and i'm very glad to have the experience.
in fact i've built all but one pair of the wheels i'm currently using.
there are, however, a lot of people who should probably not be building
their own wheels. or cooking their own food for that matter...

Food can be cooked?

--
Tom Sherman – Quad City Area

"Roger Zoul" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

If I dent a rim, I don't expect to get that fixed
for free.

A sloppy job with a mediocre spoke wrench led me to strip a
few nipples on my rear wheel. My LBS says the wheel must be
entirely rebuilt, that the rim and all the spokes are shot, which
is [censored]. The wheel has maybe 2-3K miles on it, and the rim was
just barely out of true when I took it in.

I couldn't get a straight answer from the dude on the phone:
How much for the full re-build vs. a re-build with the old rim but
new spokes vs. just replace the few bad spokes (which of course he
claims is eight or so vs. the maybe 3-4 which are actually nicked)
and true it up. Instead he wanted to go on and on about how a
damaged nipple makes it impossible to get the spoke off without
slicing it under pressure, which of course will warp the rim and
make it unusable, so a full re-build with a new rim and all new
spokes is the only answer.

Shop owners: If a guy doesn't have the ability to converse on
the phone and doesn't give a [censored] about the price a customer has
to pay, Don't let him talk to customers!

Rico in Sacramento

Bill-<< A sloppy job with a mediocre spoke wrench led me to strip a
few nipples on my rear wheel. My LBS says the wheel must be
entirely rebuilt, that the rim and all the spokes are shot, >><BR><BR>
<< Shop owners: If a guy doesn't have the ability to converse on
the phone and doesn't give a [censored] about the price a customer has
to pay, Don't let him talk to customers! >><BR><BR>

Why not trundle into the shop and show somebody the wheel. Many conversations
about bicycle stuff is made more diffucult over the phone.

Plus as a shop owner and wrench, try to take it easy on the bike shop guy, it
was you who gooned the nipples up in the first place. When he has to cut spokes
out with a fully tensioned wheel, it may just kill the rim. When he kills it
bcause you killed a bunch of nipples, and he just replaces the spokes(4 or so)
and the wheel goes to hell on the first ride, he will be blamed for that as
well.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Rico X. Partay said:

How much for the full re-build vs. a re-build with the old rim but
new spokes vs. just replace the few bad spokes (which of course he
claims is eight or so vs. the maybe 3-4 which are actually nicked)
and true it up. Instead he wanted to go on and on about how a
damaged nipple makes it impossible to get the spoke off without
slicing it under pressure, which of course will warp the rim and
make it unusable, so a full re-build with a new rim and all new
spokes is the only answer.

If it were my wheel, I'd release the tension in all the spokes. Then
I'd replace the 8 spokes on the drive side that stick out and get
damaged. It wouldn't matter if I unscrewed the nipples or cut the
spokes. I'd reuse the good nipples. I'd rebuild the wheel. The shop
should charge for 8 spokes and nipples and a rebuild. Of course, when
the wheel was released, if the rim were bent, I'd replace the rim.

Quoted message said:

Plus as a shop owner and wrench, try to take it easy on the bike shop guy, it
was you who gooned the nipples up in the first place. When he has to cut
spokes
out with a fully tensioned wheel, it may just kill the rim. When he kills it
bcause you killed a bunch of nipples, and he just replaces the spokes(4 or
so)
and the wheel goes to hell on the first ride, he will be blamed for that as
well.

Peter Chisholm

If I didn't know it already, the above is proof to me that Peter is a
real live shop guy with real live experience.

For every anecdote of lazy/stupid/ignorant wrenches, I could tell you
many more about customers who are uninformed, crooked, know-it-alls. In
bicycli as in other pursuits, a little knowledge is a dangerous thing.

--
Ted Bennett
Portland OR

"Qui si parla Campagnolo " <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

When he has to cut spokes
out with a fully tensioned wheel,
it may just kill the rim.

"May" is the operative word. Sure, that could happen. But it
might not. The guy saying the rim is shot when he's looking at an
undamaged rim is just silly. He could say, I'll give it a try, but
the rim might get damaged in the process. That I could live with.
But saying a full rebuild is the only solution when it's obviously
not is nonsense.
And I did take the wheel in in person. The referenced
conversation was when he called me up days later, saying that he
essentially didn't want to do the work.

Quoted message said:

When he kills it
bcause you killed a bunch of nipples, and he
just replaces the spokes(4 or so)
and the wheel goes to hell on the first ride,
he will be blamed for that as
well.

Not correct. I'm not out to blame him for what he can't
control. Just for being dumb and trying to take unfair advantage.

Paul Kopit <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Rico X. Partay said:

How much for the full re-build vs. a re-build with the old rim but
new spokes vs. just replace the few bad spokes (which of course he
claims is eight or so vs. the maybe 3-4 which are actually nicked)
and true it up. Instead he wanted to go on and on about how a
damaged nipple makes it impossible to get the spoke off without
slicing it under pressure, which of course will warp the rim and
make it unusable, so a full re-build with a new rim and all new
spokes is the only answer.

If it were my wheel, I'd release the tension in all the spokes. Then
I'd replace the 8 spokes on the drive side that stick out and get
damaged. It wouldn't matter if I unscrewed the nipples or cut the
spokes. I'd reuse the good nipples. I'd rebuild the wheel. The shop
should charge for 8 spokes and nipples and a rebuild. Of course, when
the wheel was released, if the rim were bent, I'd replace the rim.

Yup.. that's the way to go...last time I checked the nipples had a
slot on the other end that ya' could usually stick a screwdriver into
no matter how mashed the exterior flats were...

On Wed, 14 Jul 2004 06:45:46 -0700, "Rico X. Partay" <[email hidden]>

Quoted message said:

"Qui si parla Campagnolo " <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

When he has to cut spokes
out with a fully tensioned wheel,
it may just kill the rim.

"May" is the operative word. Sure, that could happen. But it
might not. The guy saying the rim is shot when he's looking at an
undamaged rim is just silly. He could say, I'll give it a try, but
the rim might get damaged in the process. That I could live with.
But saying a full rebuild is the only solution when it's obviously
not is nonsense.

I'm not a bike mechanic, but I do retail repair for a living - I've seen this
scenario. Maybe he used to say "I'll give it a try" but it cost him money every
time, so he stopped. Let's play this out... Do it his way and he quotes a price
and sits down with new, clean, known-good parts and assembles some good, true
wheels that he can stand behind and feel good about. Do it your way and he
fusses with a bunch of used and dirty parts; goes and hunts up some exact-match
spokes and nipples for whatever was on your wheels. Maybe he's got em all, maybe
not. THEN, he gets to play phone tag with you to get an approval on every spoke,
nipple and rim. When he's done he's got shiny spokes and dull ones, maybe he
trusts the rims and maybe you'll sue his ass off after you crash. This is a
difference between a couple hours of reasonably profitable honest work and an
unrewarding PITA job.

And just to point it out, when you say it's an undamaged rim, you're asking us
to take the word of someone who obviously hasn't got the skill to true, much
less build a wheel. At this point, I believe him.

You sound like my people who say "there's nothing much wrong with the amp, it
just keeps blowing the fuse."

Quoted message said:

And I did take the wheel in in person. The referenced
conversation was when he called me up days later, saying that he
essentially didn't want to do the work.

Why don't you believe him? He does this all the time, take his word for it.

Quoted message said:

Quoted message said:

When he kills it
bcause you killed a bunch of nipples, and he
just replaces the spokes(4 or so)
and the wheel goes to hell on the first ride,
he will be blamed for that as
well.

Not correct. I'm not out to blame him for what he can't
control. Just for being dumb and trying to take unfair advantage.

All he wants is a chance to do good work for profit. At this point you're
disagreeing with him on both points.

Ron

"RonSonic" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Not correct. I'm not out to blame him for what he can't
control. Just for being dumb and trying to take unfair advantage.

All he wants is a chance to do good work for profit. At this point you're
disagreeing with him on both points.

The scenario i get all them time ... everyone says "I want to make money for
my work" ... but make that person a customer and he will imply to shop owner
"I want you to make money, but not on me". We get thrashed wheels ... bent
sprockets, cranks and more. And people want us to fix them for $5 ... we
turn that down. Why?? Let's say we fix it the easy way ... then it brakes
and causes injury, guess where they go?? Bring it to a shop to get it fixed
right ... otherwise do it yourself.

s
http://boardnbike.com

billg-<< Not correct. I'm not out to blame him for what he can't
control. Just for being dumb and trying to take unfair advantage. >><BR><BR>

Not being personal but speaking 'generally' of what you sometimes see in the
bike shop trenches.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

"RonSonic" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Maybe he used to say "I'll give it a try" but
it cost him money every time, so he stopped.

So every time he tried to do some work that took a little
dexterity he messed it up. And therefore every subsequent customer
must pay more as a result. Great.

Quoted message said:

Do it your way and he
fusses with a bunch of used and dirty parts;
goes and hunts up some exact-match
spokes and nipples for whatever was on your
wheels. Maybe he's got em all, maybe
not. THEN, he gets to play phone tag with you
to get an approval on every spoke,
nipple and rim. When he's done he's got shiny
spokes and dull ones, maybe he
trusts the rims and maybe you'll sue his ass
off after you crash. This is a
difference between a couple hours of reasonably
profitable honest work and an
unrewarding PITA job.

What nonsense. Your assuming the wheel has non-standard parts
(or that it's too much trouble to match parts to bikes), and that
he needs approval for "every spoke, nipple and rim," neither of
which are the case. Nobody's going to sue anyone; that's also
ridiculous.

Quoted message said:

And just to point it out, when you say it's
an undamaged rim, you're asking us
to take the word of someone who obviously
hasn't got the skill to true, much
less build a wheel. At this point, I believe him.

Now you're just making things up. I trued that wheel many
times just fine over a couple of years. I just needed some spokes
replaced, for chissakes. Your defending an obnoxious guy out of
some weird kind of knee-jerk assumption that the customer is
always wrong. FYI: Many bike shops "mechanics" are often wrong.

Quoted message said:

All he wants is a chance to do good work
for profit. At this point you're
disagreeing with him on both points.

Gosh you're full of it. FYI: A guy at the second shop said,
I'll try to do the fix-up, but if the rim gets damaged in the
process I'll have to replace it and rebuild the wheel. I said,
Fine.

See how easy it is to be honest and reasonable?

Rico X. Partay wrote:
{major snippage}

Quoted message said:

I trued that wheel many times just fine over a couple of years. I just

needed some spokes replaced, for chissakes.

OK, I have a question: why did you need the services of a mechanic "just to
replace some spokes, for chissakes (sic)"?!?

Bill "assuming normal wheels, of course" S.