Recycling Bicycle Spokes

Any thoughts, pro, con, or tech?
Doug Goncz Replikon Research Seven Corners, VA 22044-0394

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The Dougster wrote:

Er, <http://www.sheldonbrown.com/brandt/reusing-spokes.html ?
--
Tom Sherman - Behind the Cheddar Curtain


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Johnny Sunset aka Tom Sherman wrote:

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.
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Nate Knutson wrote:

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 fatique life.
Dan
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snipped-for-privacy@krl.org wrote:

There is considerable difference after the wheelbuilder deliberately changes the angle of the outer spokes at the hub.
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Nate Knutson wrote:

In that case I would think one would not need to keep track of which were inbound and which were outbound. It would be obvious by merely glancing at the spoke.
Dan
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snipped-for-privacy@krl.org wrote:

Perhaps, but seperating them initially is faster, and spokes with the angle bent into them are harder to measure accurately.
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Nate Knutson writes:

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".
Jobst Brandt
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threaded end , the nipple is cross threaded or the flats turn into rounds ...... BTW 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 ....
snipped-for-privacy@krl.org wrote:

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snipped-for-privacy@swissinfo.org wrote:

If one combines the writing styles of Peter Chisholm and gene daniels....
-- Tom Sherman - Here, not there. I am supporting cannibalism by eating more nuts.
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Nate, what do wheel builders mean by "stress-relieving" spokes? What is the process they use?
-- Ed Huntress
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Ed Huntress wrote:

There are many, many descriptions in the archives of this group.
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Ed Huntress wrote:

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.
Dan
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On 10 Sep 2006 14:17:30 -0700, snipped-for-privacy@krl.org wrote:

Dear Dan,
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.
Cheers,
Carl Fogel
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wrote:

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.
-- Ed Huntress
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On Sun, 10 Sep 2006 19:50:59 -0400, "Ed Huntress"

Dear Ed,
A common analogy is to "scragging" or "bulldozing" coil springs--squash 'em down hard, and see the stress relief:
http://www.ncnr.nist.gov/AnnualReport/FY1999/residual.pdf
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 springs.
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 increases.
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 hub.
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:
B D_________ _________/\/ A C
The ASCII exaggeration above is huge. The shape could be more like this: D________ B__/ _________/ C A
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.
Cheers,
Carl Fogel
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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 careful reading.
-- Ed Huntress
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wrote:

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.
-- Ed Huntress
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On Mon, 11 Sep 2006 21:30:49 -0400, "Ed Huntress"

Dear Ed,
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 stresses.
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 bend.
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.
Cheers,
Carl Fogel
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<snip>

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 guess. <g>
Whatever, it's interesting.

Have anybody tried boiling their spokes with wing of bat or eye of newt? You never know. <g>
-- Ed Huntress
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