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Old 09-20-11, 11:01 PM   #1
seymourson
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I keep popping spokes!!!

So, 4 months, 5 spokes and $125 for the LBS to fix. I need to get some spokes and start doing it myself. The questions are...how do I determine the spoke length, are all the spokes on my wheel the same length? Are the spokes on the front wheel and back wheel the same?
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Old 09-20-11, 11:16 PM   #2
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My rule for spokes is the 1st is a fluke, could happen to anyone. The second is a warning, and the third and it's usually new wheel time.

Broken spokes usually happen at ever shorter intervals until you give up, or find the reason and deal with it. 5 spokes in 4 months repaired by the same shop at $25.00 per, doesn't sound like you were well served at all so I don't blame you for wanting to go DIY.

There are plenty of good tutorials on wheel building, and you should read at least two before starting. Any will answer the questions you asked here and then some. If speaking of a typical build pattern all front wheel spokes are the same, and the rear uses 2 lengths because of the asymmetry between the right and left sides. Usually the left rear spoke is the same or very close to the length of the front spokes, and the right rear is usually 2mm or so shorter.
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Old 09-20-11, 11:25 PM   #3
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This will get you started with decent info:

http://sheldonbrown.com/wheelbuild.html

It also has links to spoke calculators as well which will help you determine what length spokes you need based on your wheel and hub.

I think broken spokes can also be caused by improper tension of the spokes - making them weak.
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Old 09-20-11, 11:27 PM   #4
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My bet is that your LBS just does a quick insert of the replacement spoke - brings the rim back in line and calls it done.

In other words - they haven't bothered to bring the wheel into spec tension-wise - roughly 20 minutes of additional work.

Hence you keep breaking spokes...

Find a new LBS.

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Old 09-21-11, 12:38 AM   #5
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My bet is that your LBS just does a quick insert of the replacement spoke - brings the rim back in line and calls it done.

In other words - they haven't bothered to bring the wheel into spec tension-wise - roughly 20 minutes of additional work.
Which wouldn't matter much unless they replaced all the spokes on the side and stress relieved.

Spokes fail due to fatigue, with the number of cycles survived dependent on cycles (about 750 per mile as they pass the bottom of the wheel and unload, the same for all spokes in the wheel), stress cycle magnitude (your weight doesn't change as the wheel rolls so this is also the same), and average stress (mostly what's left from the elbow forming operation when you haven't stress-relieved with this being about the same in all spokes, with a little from the average tension so all the spokes in the side are about the same).

Once one spoke has failed due to fatigue all of them within that set (front, rear drive side, rear non-drive side) are close to their life limit.

The right fix is to read Jobst's book _The Bicycle Wheel_, replace all the spokes in the failing side(s), correct spoke lines, achieve high uniform tension (use a Park tension meter on deeper wheels), stress relieve, and be happy for the next few hundred thousand miles (you'll need to replace the rims as brake tracks wear out or your crash them and deal with bearing wear).

Last edited by Drew Eckhardt; 09-21-11 at 11:00 AM.
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Old 09-21-11, 02:29 AM   #6
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Is it the same spoke each time? Can you see a pattern to the spoke breakages?
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Old 09-21-11, 07:18 AM   #7
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(use a Park tension meter on deeper wheels)
Don't you mean on lower spoke count wheels?
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Old 09-21-11, 09:00 AM   #8
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I've been having the same problem. I had maybe three spokes break in my whole life, and then suddenly last year they started breaking often. Only on my rear wheel, and I think only on the drive side. After 5 or 6 broke, I bought a new rear wheel. But the problem continued at almost the same rate.

At first I thought it was because I'd gotten so heavy in my dotage. But the weight gain happened over many years, whereas the spoke breakage started suddenly last year. And since it started I've lost 50 pounds, but the breaks continue.

I didn't think there'd been any changes in my riding habits, but after paying more attention to it I'm starting to think there were. In fact, I now suspect that the breaks happened after riding over a bump in the road while leaning on a curve. Maybe leaning creates extra stress in certain spokes? And the bump increases it even more for a particular spoke? I think maybe in the past I could see better and steer better and was more careful about bumps. And, oddly enough, I think I've been leaning more in general since turning 60.

I'm trying to avoid that combination of bumps and leaning, to see if it solves the problem. It would take many months of no breakage to draw any conclusion, and even then it wouldn't necessarily apply to anyone else's experience, but maybe changes in riding habits are something to consider.
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Old 09-21-11, 09:12 AM   #9
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Once one spoke has failed due to fatigue all of them within that set (front, rear drive side, rear non-drive side) are close to their life limit.
Yep. Time to get the wheel rebuilt.
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Old 09-21-11, 09:37 AM   #10
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How's the rim? If it's worn, I would just recommend replacing the entire wheel otherwise, spokes only.
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Old 09-21-11, 09:51 AM   #11
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This is why I joined this forum. I recently paid $27 at the LBS to replace a rear wheel spoke. I thought that was expensive, but I guess this is not a bad price, especially since I was able to pick it up in an hour or so. I figured I should get the tools, and start doing the job myself. But, now it looks like if breakage continues, I may come out ahead to just have the wheel rebuilt properly and be done with it. Which I probably would not want to do myself.

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Old 09-21-11, 10:11 AM   #12
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Have you ever dropped the chain off the inside of the cassette against the spokes? The hard steel of the chain will put small nicks in the spokes which will lead to their eventual breakage. If you run a "dork disk", it may prevent damage to the spokes in situations like this.
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Old 09-21-11, 10:25 AM   #13
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My best friend had the same issue on a bike that he got from his dad. It is a 1999 Trek Y3 that has sat for the past 5 years (since his dad got his Trek Liquid) and when he since he started riding it this summer he has broken close to 5 spokes. He has decided to respoke the wheel seeing as it has a pretty good bontrager rim and shimano hub. You are either gonna have to either get a new wheel or respoke your current one.

Also, make sure to check the spokes your LBS is putting into your wheel. The LBS that was replacing the spokes for my friend for some reason was using the wrong sized spokes. He had one spoke that was so long that it went through the second wall of the rim and into the tube and he had another one that was double butted (the rim has regular spokes). Needless to say, he isn't going to that LBS anymore.
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Old 09-21-11, 10:59 AM   #14
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Have you ever dropped the chain off the inside of the cassette against the spokes? The hard steel of the chain will put small nicks in the spokes which will lead to their eventual breakage. If you run a "dork disk", it may prevent damage to the spokes in situations like this.
When I got my wheel back, after getting the spoke replaced, I noticed that the "dork disk" was gone. I asked the shop about this, and they said that they usually take them off, and never install them on new bikes. Should they have given me the option of keeping it? How do the pros feel about the "dork disk"?

Thanks, RSBG
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Old 09-21-11, 11:10 AM   #15
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Don't you mean on lower spoke count wheels?
I meant deeper wheels although too few spokes would call for a tension meter too.

The tension limit on traditional shallow box section rims with enough (32, I'd guess 28 but never built such a wheel before getting a tension meter, maybe less) spokes comes from the rim's elastic limit.

Per Jobst Brandt you can alternately increase tension and stress relieve until the wheel deforms in waves at which point you decrease tension half a turn, true, and be happy until you replace the rim.

The last front wheel I built that way measured 110kgf average without a tire; last rear 110kgf drive side with which are exactly what I'd do with a tension meter on the front wheel and perhaps a little more in back (inflating the tube decreases spoke tension so 110kgf with tire is a little more than 110kgf without).

With deeper (and therefore stiffer, with beam stiffness proportional to the cube of height) rims at the very least you'd end up with spokes that are too tight leading to fatigue issues in the spoke bed (cracks around the holes) and perhaps spokes.

With too few spokes the per-spoke tension to get there could lead to similar issues.

Last edited by Drew Eckhardt; 09-21-11 at 11:19 AM.
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Old 09-21-11, 11:10 AM   #16
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Here we go again with the dork disks...

I say they must die.
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Old 09-21-11, 11:16 AM   #17
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I've been having the same problem. I had maybe three spokes break in my whole life, and then suddenly last year they started breaking often. Only on my rear wheel, and I think only on the drive side. After 5 or 6 broke, I bought a new rear wheel. But the problem continued at almost the same rate.

At first I thought it was because I'd gotten so heavy in my dotage. But the weight gain happened over many years, whereas the spoke breakage started suddenly last year. And since it started I've lost 50 pounds, but the breaks continue.

I didn't think there'd been any changes in my riding habits, but after paying more attention to it I'm starting to think there were. In fact, I now suspect that the breaks happened after riding over a bump in the road while leaning on a curve.
It might be what finishes the spokes off but they were already in the process of breaking from fatigue.

Quote:
Maybe leaning creates extra stress in certain spokes? And the bump increases it even more for a particular spoke?
Bumps decrease tension in the bottommost spokes.

Quote:
I'm trying to avoid that combination of bumps and leaning, to see if it solves the problem. It would take many months of no breakage to draw any conclusion, and even then it wouldn't necessarily apply to anyone else's experience, but maybe changes in riding habits are something to consider.
As noted spokes fail due to fatigue. All your drive side spokes got close to their limit before you lost fifty pounds and a few went past it. You're just seeing the last of them fail.

Riding habits don't have anything to do with it. Weight and mileage (about 750 stress cycles a mile as the spokes rotate past the bottom of the wheel and unload) do.

Properly built wheels don't break spokes, although good wheel builds don't maximize profits for big bike companies so they usually don't happen.

Last edited by Drew Eckhardt; 09-21-11 at 11:20 AM.
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Old 09-21-11, 11:22 AM   #18
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How do the pros feel about the "dork disk"?
alternate name is spoke protector , and they do take the brunt of a over-shifting rear derailleur.

nobody follows me with a spare wheel like the racers do so I leave them on.

I have had a wheel wipeout in the past, cutting 25% of the wheels spokes in a second.

It's not a perfect world.
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Old 09-21-11, 12:23 PM   #19
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alternate name is spoke protector , and they do take the brunt of a over-shifting rear derailleur.

nobody follows me with a spare wheel like the racers do so I leave them on.

I have had a wheel wipeout in the past, cutting 25% of the wheels spokes in a second.

It's not a perfect world.
I'm inclined to feel the same way, though fortunately, I haven't had a wheel wipeout. But, sometimes I find myself in some pretty remote places. And, nobody follows me either.
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Old 09-21-11, 12:52 PM   #20
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How do the pros feel about the "dork disk"?

Thanks, RSBG
Why does it matter what the "pros" think?
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Old 09-21-11, 01:31 PM   #21
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Why does it matter what the "pros" think?
It matters for the same reason a smart person would seek out a professional mason on a brickwork question. A professional wrench often has more experience than the average home mechanic.
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Old 09-21-11, 05:29 PM   #22
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When I got my wheel back, after getting the spoke replaced, I noticed that the "dork disk" was gone. I asked the shop about this, and they said that they usually take them off, and never install them on new bikes. Should they have given me the option of keeping it? How do the pros feel about the "dork disk"?

Thanks, RSBG
Make them put it back, and find a better shop. It was there when they started working on it, you didn't tell them to take it off, they didn't ask, it damn well better be when they finish. They're either lazy (it has to come off to replace a drive side spoke, maybe they forgot to put it back, and don't want to bother, and are selling you a line) or they're arrogant ("We know what our customers need, and we'll give it to them even if it's not what they want"). Either way, they're not professional, and are the sort of place I'd avoid.

I say that even not having terribly strong opinions about dork disks. I'd never take the cassette off to remove one, but I don't put them on the wheels I build usually, either.
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Old 09-21-11, 05:33 PM   #23
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It matters for the same reason a smart person would seek out a professional mason on a brickwork question. A professional wrench often has more experience than the average home mechanic.
The only real objection to them is that they're ugly or uncool or will give you cooties. Their mass doesn't matter, nor does any aerodynamic inpact to anyone who isn't racing, and they can stop an overshifted derailleur, so they do have a practical use.

It's highly unprofessional to work on something and fail to put all the parts back on it, unless you're instructed to remove it.
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Old 09-21-11, 05:34 PM   #24
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Buy a new wheel. The one you have is bad.
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Old 09-21-11, 05:38 PM   #25
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I've been having the same problem. I had maybe three spokes break in my whole life, and then suddenly last year they started breaking often. Only on my rear wheel, and I think only on the drive side. After 5 or 6 broke, I bought a new rear wheel. But the problem continued at almost the same rate.

At first I thought it was because I'd gotten so heavy in my dotage. But the weight gain happened over many years, whereas the spoke breakage started suddenly last year. And since it started I've lost 50 pounds, but the breaks continue.

I didn't think there'd been any changes in my riding habits, but after paying more attention to it I'm starting to think there were. In fact, I now suspect that the breaks happened after riding over a bump in the road while leaning on a curve. Maybe leaning creates extra stress in certain spokes? And the bump increases it even more for a particular spoke? I think maybe in the past I could see better and steer better and was more careful about bumps. And, oddly enough, I think I've been leaning more in general since turning 60.

I'm trying to avoid that combination of bumps and leaning, to see if it solves the problem. It would take many months of no breakage to draw any conclusion, and even then it wouldn't necessarily apply to anyone else's experience, but maybe changes in riding habits are something to consider.
You've replaced the wheel, so my guess is your frame is bent.
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