One of the questions I have about what Jobst says is whether it would
be an issue to remove spokes from their wheels and use them in new
wheels if you kept track of which were inbound and which were outbound.
This would cause some change in what form they would optimally be set
to coming out of the hub, but usually not very much (although I could
think of some instances where it may be more considerable). I think one
would need to answer some questions here to take spoke re-use to
extremes. I have a bunch of spokes that have been in previous wheels of
mine that I've unlaced and put in bunches that says "296-outer", etc,
but I haven't started experimenting with this yet.
It should be noted that Jobst is talking about quality, stainless steel
spokes that were stress relieved by the wheelbuilder to begin with.
Spokes that have never been stress relieved can be assumed to have
accumulated some amount of fatigue, weakening them and (by my
understanding) possibly putting at least some spokes beyond the point
where stress relieving them now will prevent breakage in the future. So
if you start re-using lots of spokes from random wheels, some (perhaps
many) will break eventually even if they get stress relieved at the
start of their new life.
Re-using non-stainless spokes of any kind is probably not worth it -
you're likely to run into corrosion problems on most of the wheels
you'd be getting them from, and you can pretty much assume none of them
have ever been stress relieved.
It is always interesting to read about things like high end electronics
and high cost bicycle equipment.
When one buys new spokes, do they come in two packs, one for inbound
and one for outbound? My guess is that they do not. There is not a
lot of difference in the angle.
What would be an interesting experiment, would be to lace up a wheel
with used spokes. And lace it with half of the wheel having spokes
where the used inbound spokes are used for inbound and the used
outbound spokes are used for outbound.
But with the other half of the wheel laced where the used inbound
spokes are used as outbound spokes, etc. One could use the valve hole
to keep track of which side of the wheel had the position preserved.
When bike spokes fail, do they normally fail at the hub end? Or do
they fail at the threaded end?
I am also interested in how the wheel builder stress relieves spokes.
And does an additional stress relief after some use affect the fatique
life. I would think that one could increase fatique life by stress
relieving before ever using something, but question whether performing
an additional stress relief after some amount of use, would add to the
It's worse than that. Depending on whether they are left or right
spokes from a rear wheel you have at least three elbow bend effects
from inside to outside spokes. This is not a good idea for the
reasons stated here often... and in "the Bicycle Wheel".
threaded end , the nipple is cross threaded or the flats turn into
I use old cassette bearing botom brackets that have the strate
15 mm ? shaft , put 6003 bearings on and taper the 6003 outer race
and hog out the shell .....
20 years of "low" friction riding ! The friction is lower
than a $200 Campy !
Next i'll do bulk 15mm hard steel tubing and
cut an old bike hub and push this tube
into it .
Next mod the fork to hold the outer race of a 6002 2rs
and slip the bearings on the "shaft" , but the quick release
is now 2 clamps that bind the 6002's into their beds on the fork .
But rear hub is more exciting . It can be very rigid now ,as the
bearings are no where near the hub ! Its one piece !
can be made stronger ...
Shifters must be general purpose spring return levers that return
so you can pull again if it did not go far enough . Too much
and you must pull the other lever next to it .
was it 3 pulls or 4 for 7 th gear ??? No , just pull til noise stops
Welded alum frames maybe worse than brazed ...
why cant they heat treat the dbl butted alum tube and braze it into
alum lugs , worked OK on steel for 100 years ....
I looked at the rec.bicycles.tech use group briefly and found that
"Stress Relieving" in the bike world seems to mean cold forming to
improve alignment. My ideas of stress relieving aren't close to
theirs. I was picturing using a torch to heat the spokes and wondered
how they controled the process.
On 10 Sep 2006 14:17:30 -0700, email@example.com wrote:
Whew! Glad that you checked before experimenting.
Despite the flames that accompany the topic, pairs of spokes are
squeezed together to raise tension, not toasted.
Posters who believe that squeezing spokes together raises tension and
relieves residual stress might disagree with your description of the
process as "cold forming."
They do bend/cold-form the spokes to get the spokes to lie flatter
against the hub flange and to change the entry angle at the rim. These
bends are visible.
But I think that they see this as entirely different from squeezing
the spokes together to raise tension in hopes of relieving residual
stresses. Spoke-squeezers often emphasize that this is a microscopic
change, and they insist that it is not cold-forming.
"Cold-forming" tends to suggest "strain hardening," which is sometimes
a sub-topic in the debate. In general, spoke squeezers say that what
they do involves stress-relief, not work or strain hardening, and is
entirely different from bending things to improve the spoke line.
Sometime I have to look into this. As the former materials and heat-treating
editor for metalworking magazines, I have to see how they claim that any
kind of cold work is going to relieve stress in any grade of steel -- with
the single exception of high-frequency vibratory stress relief.
I don't doubt that it does something useful, but relieving internal stresses
at a "microscopic level" by low-frequency cold work of any kind would be a
new one in the world of metallurgical science.
Artisans in a number of fields use the term "stress relieving" differently
than engineers and scientists do. There's nothing wrong with that but it
does lead to some confusion.
A common analogy is to "scragging" or "bulldozing" coil
springs--squash 'em down hard, and see the stress relief:
One problem is that if you read the captions carefuly, you learn that
the data for the bulldozed springs is not actually given, though it's
said to be "essentially the same"--the pictures are for heat treated
Another problem is how much extra tension or compression is involved.
The coil springs are usually mashed flat.
General theory on RBT held that the impressive bend angle produced by
squeezing spoke pairs must indicate even more impressive tension
But when I measured the actual tension increases, it appeared that the
rim deformed far more than expected, rendering calculations based on
angles and an unchanging distance between the rim and hub useless.
That is, good-faith calculations based on the bend angle produced by a
30-lb squeeze force on a single spoke's midspan indicated that a
250-lb initial tension rose about 150 pounds, to 400 pounds. The
calculation assumed a basically fixed distance between the rim and
But when I measured various rear and front wheels, 32 and 36 spoke,
with and without box section, eyelets, and sockets, I found that a
60-lb squeeze force on each of two pairs produced tension rises of
only about 55~65 lbs.
With two spokes A & C pulling the rim to one side, and two spokes B &
D pulling the rim to the other side, the rim probably goes into a
faintly Z, S, N, M, or W zigzag shape:
The ASCII exaggeration above is huge. The shape could be more like
Given the extremely stiff materials and tiny range of elasticity, it's
understandable that the deformation wasn't noticed. If you tape a
spoke flat against a rim at a tangent, you can sight along the spoke,
squeeze a spoke or two near that rim section, and see the spoke swing
in or out as the rim starts to zigzag.
Discussion of spoke squeezing usually becomes quite vehement.
As far as I know, the theory is unknown in spoked motorcycle and
sports-car wheels, but they may use such massive spokes that
bicycle-style problems are masked.
Some wheel manufacturers use presses to seat spokes and may claim that
it's stress-relief akin to squeezing all the spokes at once, but as
far as I know, they release no data, and posters who cite such
practices as proof of stress-relief routinely scoff at other
manufacturing techniques as marketing-driven superstition.
Wow, you've really made a study of this. I'm going to re-read your message
tomorrow when I have time. However, let me make one point now.
I don't know the term "scragging," but "bulldozing" a spring refers to
squashing it until you've driven it as far as you can into the plastic
range. Car customizers do it to lower ride height without increasing spring
rates (cutting a coil spring results in a surprising increase in stiffness).
Car manufacturers also sometimes do it, as in the case of the Ford springs
cited in the NIST paper, in order to prevent further plastic deformation in
service, which would result in premature sagging of a car's springs.
It isn't about stress relief. If I read the NIST paper correctly, their
point is that the tempering (low-temp heat treatment) does the
stress-relieving. What they're saying about the bulldozing is that it
doesn't *increase* the residual stress, because bulldozing results in a
nearly pure torsional strain on the spring material, which doesn't produce
antagonistic stresses within the bulk of the material. It's all plastically
deformed in one direction, which results in a strain gradient but no
residual stresses result from the operation.
Anyway, that's how I interpret the NIST results, based on what they say in
the paper and also on standard engineering understandings of stress and
strain. I'll look more carefully at your message tomorrow. It deserves a
OK, I read your post carefully tonight. I'm probably not following the whole
explanation but I don't see any place where stress-relief could occur.
You're changing tensions, probably, and there's probably some plastic
deformation going on that changes the preloads and load angles -- in which
directions, I can only guess.
But the standard engineering definition of residual stress refers to
internal tensions and compressions that are due to differential expansion or
contraction within the material. For example, when you heat-treat a thick
piece of carbon steel, you typically have martensite on the outside and
ferrite on the inside. Martensite is less dense than ferrite, which means
the outside has expanded. Thus, the ferrite inside is loaded in sheer
against the martensite on the outside. It may not bend the material if the
heat treatment is uniform, but the skin and the core are both under stress,
which is residual stress from the effects of heat treatment.
Tempering (heating to a temperature somewhat below the critical temperature)
will relieve some of the stresses by a couple of mechanisms; the one that's
relevant here is allowing a slight slippage at grain boundaries due to the
elevated temperature (purists will also note that tempering converts a small
fraction of the martensite back into ferrite, thus lowering the differential
expansion/contraction). Normalizing, which is conducted at higher
temperatures, relieves still more stress. "Stress-relieving," done at still
higher temperatures and for longer times, relieves still more. Heating above
the critical (Curie) temperature and cooling the piece slowly will anneal
it, which should eliminate all internal stress if it's done properly.
That's the documented way to stress-relieve steel that has residual
stresses. There is a cold method known as vibratory stress relief which
remains somewhat controversial but which does seem to relieve at least the
more severe stresses, as from welding.
I've not heard of any cold-working method other than sustained
high-frequency vibration that relieves internal stresses. But I've been away
from the field for a few years and I may have missed something anyway. Just
projecting from the standard theory and practice, though, I can't see any
way that just squeezing spokes as you describe could actually relieve
residual stresses in a spoke.
I'm open to further education on the subject.
It does seem to be a theory confined to RBT.
It dates from at least 1981.
Others have expressed skepticism.
I'm just trying to describe the theory and practice, not endorse them.
As I understand it, the theory is that cold-bending the spoke elbow
and rolling the threads at the nipple end leave residual internal
The spokes are then often bent a little bit more, in order to make the
elbow end lie flatter against the hub flange and to make the nipple
end bend at the nipple (if necessary) instead of a longer, gentler
The theory is that your squeeze all the spokes, two pairs at a time,
after the wheel is built and thus relieve the residual stresses.
Like you, I'm open to further education.
When I measured actual tension increases in spoke pairs squeezed with
known forces on various wheels, the results were greeted with comments
including "impossible," "must be cheesy wheels," and similar
incredulity. My measurements can be easily checked, but so far no one
has announced any different results.
The topic sometimes smacks more of faith than physics.
Yes, I realize that. I didn't mean to imply that you did.
That's probably true.
I suspect -- and I'm really only guessing -- that they're seating the elbow
end, thus reducing the specific stress (the stress per unit area) at that
end. If the nipple itself is bent, you'd be transferring a load on the spoke
to a load on the nipple, which could be better. But bending the spoke at
that end, if that's what they're doing, probably does not increase strength.
I'll hypothesize one other thing: The process may actually result in a more
gradual takeup and relief of tensile stress as the wheel rotates. Some
process relating to spoke life (which may, or may not, be "fatigue" in the
engineering sense of the word) probably benefits from that, because a lot of
life-determining events in steel mechanical parts involve the strain-rate
sensitivity of steel.
I'm not going to guess beyond that. I'm already over the top with that
Whatever, it's interesting.
Have anybody tried boiling their spokes with wing of bat or eye of newt? You
never know. <g>
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