John Ridley

OK, over the weekend I had my bike up on the rack for a clean/lube job, and found 3 broken spokes on the rear, non-drive side. This is a Giant Cypress hybrid commuting bike, ridden 110+ miles a week.

History: I foolishly took this hybrid with 700C wheels on a rather rough off-road course at a state park. The rear wheel got bent a bit (maybe 1/2" deflection max). Not knowing any better, I pulled it back true by just tightening spokes. About 4 weeks (and 400 miles of commuting) later, one of the spokes (on the drive side) broke.

At that point, I realized that I should have actually straightened the wheel, so I got a new spoke, tore down the wheel, straightened the rim on the kitchen floor (pulled on it until it laid flat), then relaced and retensioned it per Sheldon's web page.

That was a few months and about 800 miles ago. Now I've got 3 broken spokes. I think they all happened in the last week.

OK, so I replaced those spokes, and retensioned/trued.

My commute takes me over about 4 miles of gravel road. At this point it has not been graded in about 8 weeks, and the washboarding and potholes are getting bad. I actually remember hearing a couple of the spokes popping but didn't realize what it was at the time, I thought rocks had hit the spokes. The fact that the spokes are breaking now, when the road is particularly bad, leads me to believe that hitting potholes is the problem.

The problem is, I have a friend who says that spokes should NEVER break, at least not this many, and if they are then the wheel was built wrong.

I think the spokes broke because of a combination of being over-tightened for a few weeks this spring, and the rough road conditions I've been hitting lately. I'm betting that the ones that broke happened to be ones that were weakened previously.

I was planning on just buying a box of new spokes on my next Nashbar order and keeping an eye on it. It only takes 10 minutes to spin off the freewheel and put in a new spoke. I'm planning on commuting this winter (slush and salt) so it's probably a good idea for me to tear down the wheel and clean and re-lube the nipples in mid-season anyway or the whole thing will rust solid.

Any opinions? Should I expect to break spokes when I ride over 40 miles a week of washboarded/potholed gravel roads? Are the breaks likely leftover weaknesses from the abuse this spring? Or am I just building the wheel wrong? I don't have any tools other than a spoke wrench, I'm truing/dishing on the bike and tensioning by ear (which seems to me like it would HAVE to be more accurate than using a gauge).

In any case, I'm learning something, and spokes are cheap, but I'd like to learn to do it RIGHT, not wrong.

AndrewP

I think spokes have been breaking as a result of over stressing in the spring. When you rebuilt you should have done it with a new set of spokes. Congratulations on you wheelbuilding efforts - thats more than I have ever done. When you have finished the next rebuild take the wheel into a shop and ask them to check the tension with a tensiometer. Then you will have a reference for tuning by ear. Often spokes undertensioned is the start of wheel problems.

Double walled rims will also stand up to more abuse. I weigh 235 lbs and used to have lots of rim problems. Since I have been riding on 30 mm deep double walled rims my wheels have stayed round and straight.

supcom

I think that replacing the spokes is a good idea. It is possible that bending the rim put excess force on the spokes accellerating fatigue. Since you have had four spokes break in short order, you should assume there are more to follow. I don't buy the bad build argument. Maybe some marginal spoke quality starting to show itself.

Where are the spokes breaking? Normal fatigue breakage is either at the elbows or the nipples. Breakage in the middle indicates poor stress relief. Also examine the break carefully, if it is a 'clean' break that looks like it would fit back together, then you have a fatigue failure.

John Ridley

They have all broken at the bend. Each was a clean break though I did not have the rivetted down part in any case. Looked like a classic fatigue fracture to me.

I guess I'll buy two boxes of spokes and replace them all next time. I'll probably ride it as is until my mid-winter teardown unless spokes break before then.

John Ridley

In response to congrats on building the wheel, my general response when faced with something broken that I've never tried to fix before is, even if I totally screw this up, I probably won't be making it any worse if I have to pay someone to fix my mess, and I'll learn something.

The firs time, I learned to just buy the tool next time. Instead of buying the $8 freewheel tool, I had the shop spin it off. They charged me $5 bench fee for that 30 seconds work. This time I just bought the tool.

I'll have the tension checked next time. The first time I simply put the tension at about the same as the front wheel (again, by ear). The spoke lengths (hub diameter) appears to be the same on this one so I figured they should be the same pitch when plinked. This time as I didn't fully relace, I just trued the wheel.

I need to make myself a truing stand too. To heck if I'm going to pay $130 or more for five bucks worth of metal when I have a welder. I swear, you take a $10 item, write "for bicycles" on the box, and charge $150.

John E

Too little spoke tension, as well as too much, can lead to spoke breakage. Given that you are breaking left-side spokes, which are under less stress than right-side spokes because of the wheel's "dish" or offset, this may be your problem.

sakarias

I once (a couple decades ago) built a rear wheel and was plagued by broken spokes. After three or so, I finally took a close at the bend (on a spare spoke from the set) and found that instead of a nice radiused curve at the elbow, there was a sharp bend. That sharp bend would concentrate the stresses at that point and result in a spoke breaking . In other words, I had purchased a bad set of spokes. No one could have built a reliable wheel with those. I do not recall the brand, but it was one of the well know names in spokes.

Once I found that, I removed all the spokes and started all over rebuilding the wheel set -- and, checking the spokes before I installed them.

Mike