Bicycle Mechanics - Rear spoke keeps breaking.
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I have a Fuji Newest 3.0 road bike that is just under a year old. On the rear wheel, on the drive train side, at the hub, a single spoke keeps breaking, in the spring, I broke 3 at different times, within a few weeks. I kept taking it back to the shop where I bought it, and asked them if the rim was bad, and they keep saying no. Its been about four months and ive rode the bike several times without anymore problems ,until today. I was getting ready to load the bike lifted a few inches put it back to the ground and heard another spoke snap, never even rode the thing, also when this happens the rim bends. Anyone have a clue as to the problem?
09-27-08, 11:14 AM
The rim "bends" because without that spoke carrying tension, the other spokes around it are forced to carrying more tension which pulls the rim out of true. I would guess that the shop is not properly tensioning the replacement spokes (or not stress relieving it) and it's loosening up over time. A loose spoke fatigues quickly which is causing the breakage. Have it replaced again but after a few rides, bring the wheel back and have them check the tension on the spoke.
You can pluck the spokes and compare the sound to get an idea of what their relative tension is. A higher note means more tension. Rattling or a thunk means the spoke is way too loose. A strong wheel will have even tension between all spokes on the same side of the wheel (for rear wheels because of the dish) or just between all of the spokes (front wheels).
For a much better explanation, go read this: http://sheldonbrown.com/wheelbuild.html
09-27-08, 12:15 PM
It isn't the rim's fault. It's the tesion that the wheel is built with being wrong from the sounds of it. Or it could be that the spokes are cheap but far more likely it's due to the spokes being set to the wrong tension. The fact that it's the drive side all the time suggests to me that the wheel is overtensioned rather than the more common under tensioned. Although that would need to be over tensioned in conjunction with lesser quality spokes at the same time. Usually spokes are capable of withstanding so much tension that the rim will crack or collapse first before the spokes will break.
At this point it would be best to have the rear wheel be rebuilt with all new spokes and done by a good wheel builder.
09-27-08, 05:36 PM
Yeah, once a couple spokes start snapping, you can be assured that the entire set is fatigued and ready to go. If you keep on replacing them one at a time, they'll continue snapping until each and every spoke has been replaced. And even then, the process might start all over again because the new set will have started to fatigue due to the low-tension as well...
I had a 06 Newest 2.0 with the same problem. After many returns to the shop, I emailed Fuji about the problem. I was persistent and Fuji eventually replaced the wheel with an upgraded version. There was a problem with that particular set of wheels, I was not the only one with spoke issues. If it's less than a year old I'd look at warranty replacement.
09-28-08, 10:44 AM
+1 on checking into the warranty since the bike is new...
My friend bought a Rocky Mountain Sherpa (touring bike) and the factory rear wheel was total crap and it's repeated failure resulted in him having to cut a tour short.
Part of this failure stemmed from him not bring the bike in to have the wheels checked prior to his departure as new wheels often have build issues that manifest themselves after they have been subjected to use.
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