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Mavic's breaking spokes...(7 posts)

Mavic's breaking spokes...Ravik
Jul 29, 2002 11:36 AM
Has anyone else had problems with spokes breaking - at the nipple - on Mavic wheels. I've got a pair of CPX 21s for general training and for the third time in three weeks I had a spoke snap at the nipple. The LBS says it's me hitting bumps (not happening), a friend tells me he heard there was a problem with a huge production run of spokes that were over heat treated making them brittle.
Anybody know for sure or have any ideas?
re: Mavic's breaking spokes...Chen2
Jul 29, 2002 1:24 PM
How are they laced? 3X, 2X, radial? I think broken spokes are a pretty common problem with CXP21 rims if radially laced. Apparently some Cannondales came that way from the factory.
re: Mavic's breaking spokes...merckx56
Jul 29, 2002 1:44 PM
mavic doesn't make the spokes! they are probably machine built wheels that are either overtensioned or just not built very well. if you LBS says your breaking spokes by hitting bumps, find a new mechanic. if that was the case, your wheel would explode when you cross a rr track! that's a bullshit, cop-out answer from a shop that doesn't want to fix a problem!
re: Mavic's breaking spokes...curlybike
Jul 29, 2002 2:01 PM
Spokes breaking at the nipple is a fairly uncommon happening. They may have been damaged that you were not aware of and finally failing. The threads may have been rolled on improperly leaving a flaw that leads to a break. At this point you should consider getting the wheel rebuilt entirely with all new spokes and nipples by a shop that is more familiar with wheelbuilding.
Good advice. -nmTig
Jul 29, 2002 3:01 PM
re: Mavic's breaking spokes...Ravik
Jul 29, 2002 3:51 PM
I'vw gone to the LBS with your responses and they've agreed to rebuild the wheel ... of course that has a good side and a bad side to it!
I've also talked to another shop - which sponsors a club I ride with - about getting a new wheel set that's going to make TTing and Sat morning rides more fun.
Thanks for all the help!
de-tensioning and setting spokes mighty have helped roadie
Jul 30, 2002 9:40 AM
If the spokes were not "set" at the thread end to take a bend that leads away from the nipple at the propper angle, they will be flexed (and under strain). When the spoke is loaded (reaches the bottom and tension on it is relieved), that strain will let up and the spoke will striaghten. Then when the tension returns, the strain / flex returns. Rep[eated strain / flex cycles leads to fatigue and failure.

It is odd for spokes to fail at the thread that way, but that's because "setting" the threads is something most people do, sometimes even without concious attempt. Poor spoke quality would certainly exacerbate the problem- brittle spokes wouldn't set as easily and would fatigue more quickly. But even if the spokes were originally OK, they are probably shot now. They should all be replaced. De-tensioning and setting the spokes when the first one snapped might have saved the rest, for a while at least, but 3 broken spokes is a solid indication the rest are not in good shape.

Unless the wheel has really high miles, I think the wheel builder / shop should rightfully supply the all the replacement spokes (and labor, if you want it) on warranty. The "hitting bumps" claim is whack. Your rim would dent, flat spot, or taco before you'd bust spokes on a propperly built wheel. Besides, how can a bump pushing IN on a rim snap a spoke, I wonder?