spoke nipples?

Wear pasties.

It's not just the contrived illiteracy but the content that makes me
wonder what grade education stopped or never took place. The
vocabulary is out of synch with the awkward attempt at misspelling and
grammar.

What's the goal here?

Jobst Brandt
jobst....@stanfordalumni.org
Palo Alto CA

2. use a proper tool. spokey is cheap and grips the flats on 3 sides,
not just 2 like park.

3. use a tensiometer. park make one for about $50. spokes that are too
tight get hard to turn.

4. make sure your spokes are the correct length. once you run out of
thread, they get very hard to turn indeed!

5. you should not have to be doing "major adjusts" like this. if the
wheel is properly built, with quality components, properly tensioned,
and correctly "stress relieved", you should be pretty much set for the
life of the wheel.

6. enjoy.

That's all good advice, but I'd be interested in knowing why Jim is
skeptical about stress relief, as demonstrated by the quotation marks
here and his arguments with Jobst Brandt elsewhere.

I'm no materials guy, as Jim seems to be. But the theory makes some
sense to me and wide experience confirm the benefits of stress relieving
spokes. Is it improper terminology? Or is Jim simply exasperated with
guys who just unwind their spokes and call it "stress relieved"?

--
Ted Bennett
Portland OR

I think it's clear that G. Daniels has done too much Instant Messaging,
and it affected his brain.

--
Ryan Cousineau, rcou...@sfu.ca http://www.sfu.ca/~rcousine
President, Fabrizio Mazzoleni Fan Club

Two things. Make sure you oil the threads and the rim socket. You might
also want to get a Spokey spoke wrench. Under $10 and it works well.
------------
Alex

i guess "stress relief" is ok terminology because it's the common usage
for the practice of over-stressing individual spokes, but it's something
of a misnomer. but let me be clear, there is absolutely no doubt that
it is /excellent/ wheel building practice!

my skepticism is for the reason commonly given on this group for why it
works. spokes that stay properly tensioned do not usually fatigue
unless there is a reason [e.g. chain derailment gouging notches from
which cracks can grow].

from the failures i've examined, spokes that fatigued at the hub most
commonly did so because they were not properly tight and they started to
move around in the spoke hole rather than staying put through tension.
that movement started a [fatigue] stress cycle at tiny surface defects
in the spoke elbow [left over from manufacture] which nucleated classic
metal fatigue.

so, to avoid loosening, you momentarily over-tension individual spokes
using the various methods described in the books & web sites, you get a
little yielding in the hub hole and the rim eyelet, then you can tension
up the wheel properly pretty much eliminating subsequent de-tensioning
in use.

hey presto! you eliminate the primary source of fatigue initiation and
thus broken spokes!

"stress relief" does *NOT* magically "change the crystal structure" of
the spoke, does *NOT* mystically erase the cold work history of the
spoke and does *NOT* seek and destroy phantom internal stress
concentrations. neither does it sacrifice virgins on the 7th sunday of
the month. it merely allows the hub, spoke, nipple & rim to become *and
remain* "intimate" in a way that prevents subsequent loosening. just
like proper torquing of the lug nuts on your car prevents them working
loose while driving. [improperly torqued lug nuts fatigue too...]

and that's it.

jb

Well go back to your metallurgy lab and perform a fatigue life test,
take two spokes and give them a manual kink in the middle. Then after
stretching one to yield in situ and the other one as is, perform a life
test with a reasonable load. The one that was taken to yield before
the fatigue test will be completely stress free while the other will
have residual stress from the manually induced kink.

Just the same, it is highly possible that the un-yielded spoke will
not break at the kink but at the elbow or threads because they both
have fairly high residual stress. You'll note that the spoke that was
stretched to yield will be perfectly straight on removal from the
tester.

This has all been done in researching "the Bicycle Wheel."

What causes these surface defects?

I see no proof of that contention. That's a lot of "hand waving."

Stress relief relieves stress. There is an article in the FAQ that I
don't care to rewrite every time one of your ilk comes on the scene.
It has happened often in the past but slowly ebbing. You are a diehard.

http://draco.acs.uci.edu/rbfaq/FAQ/8c.1.html

> and that's it.

Interesting. That would explain how under-tensioned spokes, such as
ones on the non-drive side, fail when the higher tensioned spokes on
the drive side don't. This problem ought to be fixed by "improving
the spoke like", as Jobst calls it.

Off to the garage to replace my rear rim (it was struck by a car
this morning).
--
terry morse Palo Alto, CA http://www.terrymorse.com/bike/

osteoporosis?

harumph??

one wonders if a serious touring vector lies somewhat above the purveyed
world grade nipples and spokes?

and if a solution can be had??

and, off course one wud have more fun without surf nazis and withering
nipples !! not that down time is without reward butt butt butt
zuviel est, no?

and i ran into-or explained another nipple ow ow ow ow problem this
morn when two more spokes pulled out whilst trying to align after
another unseen session of vandalism at the rack. spare rim and
cluster(clack clack). on the road commuting i conjured a reason-the in
shop made spokes were made with a worn tol head?? thus less thread
percentage and more probable pullout??

back to the distributor's cut spokes??

sorry jobst zooooooooooooooooooooooooooooooooooooooooommmm!!!!

"completely stress free"??? what is cold work? what is dislocation
density? how are spoke wires drawn? are they annealed before
deployment? this claim does not accord with even a basic understanding
of materials.

drawing dies, bending mandrels, inclusions, grain texture... it's a
long list. are you asking a serious question? if you are, i'm glad to
answer, but it worries me that someone with their own individual
theories for material behavior would ask such a thing. surely you've
examined broken spokes under a microscope and studied the fracture
surface? it would give you chapter & verse on how the component failed.

no, "stress relief" does *NOT* relieve stress in the way you keep
saying. high tensile wire [spoke wire] is fundamentally /full/ of
residual stress. it's called "cold work". repetition does not make you
any more correct today than the first day you said it. nor will it in
the future. why do you think "my ilk" keep popping up? why don't you
read a good materials book? you'd not only enlighten yourself, you'd
not give "my ilk" anything to complain about.

ISBN: 0070168938

it'll tell you all about fatigue jobst. it'll tell you about
nucleation, growth and fracture. it'll tell you about surface defects.
it'll tell you about high tensile materials and dislocations too.

jb

Uh, I think you missed the tool recommedation. The brand name of the tool is
Spokey. Not a spoke key, which is what you call the tool. Using a good tool
on well lubed nipples, I have never damaged the nipples. Something is a miss.

-----------------
Alex __O
_-\<,_
(_)/ (_)

Seconded. Costs next to nothing, grips the nipple well and it's
comfortable to use.

Huw "LBS sold me a second hand one for a quid" Pritchard

Time to check your medication level, G.

Total horsesh&t.

Everyone knows that the driveside spokes break more often, because that
forces you to REMOVE THE CASSETTE to replace 'em!

Bill "all too familiar with this phenomenon" S.

Well, you are right that stress relieving will not make it
"completely" stress free . See http://www.lanl.gov/residual/alum.html
, in that case the residual stresses were only 90% relieved, which is
about the best you can do with that type of aluminum alloy plate.

Stresses are stored elastically in the crystal lattice. Under tensile
stress, the lattice planes are farther apart, etc. Basic elasticity.
That is why x-ray and neutron diffraction can measure residual stress
by only measuring the lattice spacing without having to measure
information about dislocations.

When you anneal or thermally stress relieve a material you will reduce
both stresses and dislocations. But when you stress relieve by putting
in uniform plastic deformation, you can relive stress at the same time
you increase cold work.

There is a vast literature on stress relief BY cold work. They are
most certainly not the same thing.

Mike Prime

My opinions, not my employer's.

Sorni's Law?

I guess I'm living a charmed life. All the spoke breaks I've had in
the last several years have been on the non-drive side. On
machine-built wheels only.

Yes, Sorni's Law :)

I had an anodized Mavic 517 built with black 14g spokes (don't ask me why;
guy recommended 'em). Wheel lasted about two months before I started
breaking spokes every other ride, and they were almost always drive side.
(This was a mtb, of course; my road bike is new so no experience yet.)

Finally bought some Crossmax XL's and haven't had to touch 'em once (~3
months or so).

Bill "$$$" S.

75mm thick annealed then 3% rolled aluminum plate and 2mm high tensile
stainless wire are about as similar as tomato & prime rib. the rib &
tomato are both red & tasty, but the similarity ends there. and, with
respect, this whole debate seems to be confusing strain with stress.
the example cited describes /straining/ a sample that has a low
percentage of cold work to a slightly higher percentage in order to make
the material uniformly strained throughout and thereby mitigate
distortion effects for machining precision aerospace components.

yes, the alloy block has measurable "stress" [elastic strain] due to
it's non-uniformity, but it's simply not possible to make a direct
comparision between that most undoubtedly "macro" elastic distortion and
the profound microstrucure changes wrought on a wire that has been
strained 100% or more by pulling it through a die!

correct. the measuring methods you describe will /only/ measure elastic
stress, it's not a measure dislocation density, the result of cold work.

but i still don't see where this argument is trying to go; the
mechanical properties of the spoke, particularly its fatigue
characteristics, are the direct result of its composition, physical
nature, microstructure, dislocation density and its physical processing.
every time i put a fatigued spoke's fracture surface under the
microscope and can see a crack initiating at a surface defect,
particularly when we're talking about a material that has *no* inherent
fatigue endurance limit like stainless steel, i have difficulty
understanding why anyone would want to argue that plastically straining
the material further at this point is somehow going to make this crack
initiator go away or that its going to change a material's intrinic
properties.

but we're not achieving uniform plastic deformation here. a 1% _strain_
on a 294mm spoke will take it up to 297mm, unusable for it's original
intent. there is no measurable plastic strain caused by "stress relief"
of a spoke. if you're talking local strain, that's a whole different
ball of wax from the 75mm plate example and if anything, small scale
local strain is more likely to initiate fatigue than mitigate it.

that's the truth!

jb

i meant to say this yesterday: stainless steeel has no inherant fatigue
endurance limit. you can mitigate by trying to eliminate surface
defects from processing and inclusions from good material control, but
ultimately, it's not possible to completely make it go away. all you
can do is push it way out along the "n" axis of the fatigue graph. and
good build practice effectively achieves this.

jb

The stress or strain argument is a red herring, and it is not being
confused. For the aluminum plate, your explanation is fine, but you
can look at it just as well in terms of stress. The plate is indeed
strained in order to make the material evenly /stressed/. Since
residual stresses (but not strains) must balance over a cross-section,
the residual stresses are relieved when the load is removed and the
part unloads elastically.

Fatigue failure is not an either-or proposition. Even with a defect
present, residual stress can greatly accelerate or retard fatigue
crack initiation and growth. Nobody in this thread said that the
stress relief would change the intrinsic material properties.

Yes, you are right. However, you do not necessarily need significant
plastic strain to stress relieve. For the spokes, it does not take
much load (or strain) to bring the stresses more even over the cross
section. So long as the spokes subsequently unload elastically and
uniformly, the residual stress will then be relaxed. Not completely,
but significantly. For a material like the aluminum, where there is
still lots of strain hardening to overcome and they are trying to
achieve a much greater degree of stress relief, significant plastic
deformation is required. Yes, my example was not the best comparison

and

> ... high tensile wire [spoke wire] is fundamentally /full/ of

Which does not accord with a basic understanding the concepts.

Mike

so i turn 4-5 times and then all the niples are rounded out and i
start filing..
our local expert, g. schwin of schwin Fort Myers sez-the 6mm nipples
and the ??4mm nipples are made from the same brass pot BUTBUTBUT the
6mm, that I chose for its more fileable shaft has an achilles!! the
unthreaded area before the threaded area is longer on the 6 than the
four thus the 6 has a more pliable malleable shaft as less angled butt
up to the spoke thread's available when the wrench bears down on it. I
thoiught that was a touring 6 butbutbut maybe not...

and the suggestion that a tiawanese manufacturer has or once upon,
steel nipples. steel nipples steel nipples. has a nice ring to it.
grade 5!!!

DO STEEL NIPPLES EXIST? and off course, will a steel nipple(and i see
someone beet me to it as i logged on with a click click click post,
very very very funny hehehehh) will a steel nipple gouge the rim
insert? one can lube the steel insert but for how long??

it is interesting that the major cawment is "shudn't have this
problem" and not
"expletive deleted io get tired of it too" youse guys aren't getting
the miles in!! and the cross country people trade wheels and pack
tired wheels off to DHL or pop into the local LBS for a demitasse and
a true up!!

d'aye ze d' aye zee give me ur answer dew,
Ohm half crazee over muh luv fur u
berth!!!!

better better better??? than prose as rounded nipple??
wavy gravy!!!

1. how do residual stresses compare with stress concentration stresses.

2. how do 3-dimensional residual stresses resolve when dealing with
materials the thickness of a spoke? with high strength fibers such as
graphite & glass, one of the dominant factors in their strength is that
applied strain resolves uniaxially. a spoke is not a fiber, but below
3mm the math leans increasingly in that direction

later

j

g.daniels wrote:

Linseed oil undergoes a polymeric conversion and hardens. People use it
to *stop* nipples from turning.

If it's not stainless steel it's gonna rust/seize quickly if exposed to
any moisture. As far as stainless nipples, I think getting the threads
cut would be difficult to begin with, and in use difficult to adjust.
Stainless on stainless threads under heavy tension may not turn
anywhere as nicely as the brass nipple (galling).

I used to marvel at their claims too and had my share of wheel and
nipple problems. The more I've paid attention to the recommendations
and tried to put them into practice, the more success I've had with my
wheels -- the stuff works. I'm still occasionally stymied but I haven't
rounded a nipple recently.

Oh ohhh..he found the caps and the period keys....

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

Hardens?? with a drop of 30 wt non detergent? or detergent? and how
much breakaway torque does the oil=linseed produce?? enough to
damage a nipple surface?? maybe that adds to potential rounding damage
but the thought does recommend linseed. the mix doesn't stop nipples
from turning when turned but when ridden? maybe. or mostly.

wil linseed+oil prevent corrosion??with a steel nipple?? I see yes in
practice. An eye on the liseed+oil ‘wax' thru wet times should keep a
seal over the spoke/nipple joints. linsee+oil with steel parts exposed
to the weather is excellent practice-as long as one doesn't cycle thru
the goosedown factory.
>

> >DO STEEL NIPPLES EXIST????????????????????????????????????????????

> I used to marvel at their claims too and had my share of wheel and

what claims?
what recommendations?
what stuff?
stymied by what?

the tool idea, that is a vice like grip the nipple but without too
much pressure inward just zero clearance for that damaging side to
side wiggle or tool rock, ah TOOL ROCK!! print it. UTM…
anyway, the less clearance the better grip the less damage to the
fastner surface. My local expert, G.Schwin of Schwin FM, thought about
his experience with the vice nipple tools but couldn't remember a
specific positive over the spokey-yet logic suggests an advantage by
less tool rock. The mech doesn't send the fastner out into the vacuum
or doesn't want to anyway.

and the cross country people ..

Stress concentrations require a stress to "concentrate." They will be
acted on by residual stresses just like by applied stresses. So you
generally want to compare residual stresses to applied stresses (bulk
or macro or average or however you want to describe them in the
general region of the concentration) rather than concentrated stresses
very local to the flaw. For fatigue crack growth, for example, you
would normally compare the stress intensity factor for applied and
residual stresses, KIapplied and KIresidual. KI is a measure of stress
concentration (close enough for this discussion anyway) that is
calculated based on the applied average stress and the size of the
stress concentrator (for KI, the crack length).

The relevant difference between applied stresses and residual stresses
is that applied stresses can be cyclic. They vary over the loading
cycle, such as each time a spoke is loaded and unloaded. Residual
stresses are mean stresses, they remain constant independent of the
cyclic variations in applied stress. (If the combined stresses cause
yielding things do change.) Mean and cyclic stresses have different
effects on crack initiation and growth. It should be sufficient here
to say that they both are important, although mean stresses alone
cannot cause fatigue failure. Cyclically loaded parts are commonly
given residual compressive stresses near the surface (e.g. by shot
peening) precisely because residual stresses do have a big effect on
fatigue life.

This question does not make sense to me. You want to compare /uniaxial
applied/ loading in a fiber to /3-d residual/ stresses in a spoke.
What is the point you want to make?

sorry for not being clear - i was trying to get a quantitative answer
for the magnitude of residual stress i can expect to see in a drawn wire
- the straight section of a spoke.

agreed, but the notch sensitivity of the material comes into this
equation also. aluminum is a big beneficiary of this treatment for
instance.

size effect. smaller notched components perform better than larger ones
in fatigue.

thank you for raising some very valid and important points - i have
ignored residual stress as a factor in these failures because the
majority of the fractures i've examined initiate on the /inside/ of the
spoke elbow bend, not the outside [although i have examples of each].
residual stress in this location is compressive so i'm just looking at
the external [+cyclic] load.

when i read a theory that an essentially once-off sub-yield tensile
force in this location is going to materially affect affect fatigue
life, my b.s. detector gets triggered. especially when its author
doesn't know the difference between materials that exhibit strain aging
and those that don't. but that's my problem i guess.

thanks again

jim

WHER'S THE STEEL NIPPLES???????????????????????????????????????????????????
que? cawment on the vise type nipple tools???
nobody no??
sheeeet

Why the residual stress in the straight section? The fatigue failures
occur in the bend or the threads.

The inside of the spoke elbow will have TENSILE residual stress, not
compressive, because of the elastic springback after bending. See
below. That 0.5 Sy number is for a beam; I'm too lazy to derive the
number for a circular cross section right now.

Since that location has tensile residual stress, tensile applied mean
stress from the spoke tension and bending, plus the cyclic loading, it
is obviously a good place to start a fatigue failure.

Mike

----- copied from 1999 posting
http://groups.google.com/groups?safe=images&ie=UTF-8&oe=UTF-8&as_umsgid=%3C36BB54E...@DELETEME.lanl.gov%3E&lr=&hl=en
----------------------

The residual stresses caused by bending plastically and then unloading
elastically have the opposite sign to this. The side that was
originally
in tension has compressive residual stress and vice versa.

At the risk of having this come through poorly via ASCII, let me try
to
sketch this (try viewing with courier or other fixed-width font). The
following is the through-thickness variation of stress in a bent beam.

LOAD UNLOAD RESIDUAL
Sy -1.5Sy -0.5Sy
| \ \
| \ \
| \ \
| \ \
----- \ -----
| \ \
| \ \
| \ \
| \ \
-Sy 1.5Sy +0.5Sy

Sy = yield stress
Assumption: elastic-perfectly plastic, elastic unload
The reason the peak stresses are 1.5 Sy for unloading is that the
unloading distribution must have the same moment as the load.

Conclusion: the side originally in tension has compressive residual
stress.

A similar figure appears in the introductory textbook from which I
learned solid mechanics: "Introduction to mechanics of solids," Igor
Popov. I trust that newer textbooks contain a similar treatment.

i knew that - now that you reminded me!!!

thanks mike.

i guess i still have a question though. how does this compare to the
other factors when looking at fatigue initiation for a spoke? i ask
because there's plenty of info for residual stress [and relief] for
springs, whose alloys are highly notch-sensitive, derive their strength
from their composition and heat treatment, etc. a spoke however is
primarily the product of it's [extensive] cold work history and has very
little in common with the above.

any thoughts?

j

quick recc for the Pedro's tool too. it has both the spokey-style
three corner, and the park-style standard, on the same tool. something
like 7 bucks online, IIRC. a while back i bought one and waxed happy
about it on rbt. i was promptly informed that Pedro's stuff sucked,
and that you dont really need the three corner spoke key.

well, that was a while ago. i was young. and naieve. some hundreds of
wheel-trues later, i am still young and naieve, but i can say with
some confidence that

a) this spoke key is well made, in that the wrench parts fit the
nipple flats well. if other pedro's tools break (i wouldnt know) then
this is the exception (i like their cone wrenches, thoguh.

b) for decently built wheels you do not need a three corner tool, it
would seem. the nipple flats fit are standard and fit the tool well,
the metals are good, the nipples rarely seize, and the spokes are not
overtensioned. however, for older wheels with corroded parts, rusted
cheapo spokes, inferior OEM componentry, etc, a three corner tool can
make a difference, and the pedros version doesnt cost appreciabely
more than the spokey, and includes a 'normal' option in the same easy
package.

I'm really not sure. I generally expect the residual stress to have a
significant effect on fatigue crack growth, and, therefore, on life. I
really don't have enough information to say much about the effect of
residual stress on crack initiation in this particular application and
in regards to the factors you mention above.

Mike

This is why properly stress-relieving the spokes when building the
wheels improves durability. There are residual stresses within the
spoke at the elbow from forming the spoke.

http://www.faqs.org/faqs/bicycles-faq/part3/section-28.html

the other answer or one of them beyond stress relief(also reached by
throwing the assembly into the can and getting anew one) is
lubricating the hub before assembly-wax with teflon liberally applied
onto the spoke holes then filling the holes up with wax with teflon
allowing to set in a horizontal position. One can dribble the wax down
a used spoke(cut the end off)
The spokes, in theory, move around under load and the dry movement
contribute to spoke bend failure. That's an empirical conclusion based
on road testing to eliminate tooth gnash.

chow!

Gene, It seems you've experienced a nipple failure of some type.

If the flats are rounded, get a better spoke wrench and be sure to pull
always it down on to the nipple - don't engage from the side.

If a nipple simply cracked in half, I'd consider that a known but rare
anomaly and not worry about it, replace and ride.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

right! and the parks 6 way tool appears to be worn out!! that's a
suprise: brass vs "hi quality tool steel."

The Dt hex head nipples are choice-if one has a wheel stand to adjust
from the back.

LBS sez not much hardness difference between wheelsmith nips and DT
nips.

Two manufacturers in Tiwan exists-of steel nips-but no word so far of
a usa outlet.
>