I just found a broken spoke on my rear wheel, it’s on non-drive side. Shocking part (at least to me) is that the spoke broke while my bike was sitting in my apartment so no load of any sort. Wheels are 9 months old, have less then 5000km on them. Is this an issue with wrongly assembled wheel, manufacturing defect from Sapim side or something else? Is replacing this single spoke enough or should I have the whole wheel relaced with new (different?) spoke?
Spokes are Sapim cx ray, j bend on bitex rar9 hub. The spoke broke just above bent section where spoke gets straight,
Broken CX Ray spoke
Moderator: robbosmans
Running a shallower rim tubeless? Either the build was done poorly or the rim compressed a lot by the tire is my guess.
Measure tensions with the tire mounted and inflated next time to see that your're not too low on NDS. A thin spoke like a cx-ray should literally hurt your hand when you squeeze them. That's how tight they need to be.
If the wheel was running true until it happened then probably all NDS spokes need to be replaced.
If you've been riding with an untrue wheel for a couple of weeks then maybe it was only a one spoke issue.
Did you receive any spare spokes with the wheelset?
Pictures?
Before I learned how to get spokes lengths right I used to hear aluminum spoke nipples break at random times at home. Freaked me out too. It's caused by fatigue. The odd thing is that I only ever broke one nipple riding. The other 2-3 broke while at home. Interesting phenomena this fatigue. Anyway I stopped replacing nipples and fixed my spoke lengths. Haven't broken anything since and that was several years and many thousands of km ago.
Measure tensions with the tire mounted and inflated next time to see that your're not too low on NDS. A thin spoke like a cx-ray should literally hurt your hand when you squeeze them. That's how tight they need to be.
If the wheel was running true until it happened then probably all NDS spokes need to be replaced.
If you've been riding with an untrue wheel for a couple of weeks then maybe it was only a one spoke issue.
Did you receive any spare spokes with the wheelset?
Pictures?
Before I learned how to get spokes lengths right I used to hear aluminum spoke nipples break at random times at home. Freaked me out too. It's caused by fatigue. The odd thing is that I only ever broke one nipple riding. The other 2-3 broke while at home. Interesting phenomena this fatigue. Anyway I stopped replacing nipples and fixed my spoke lengths. Haven't broken anything since and that was several years and many thousands of km ago.
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One bad spoke is possible. There are odd ducks here and there.
I would replace it, if another one breaks change all nds.
I don't really like cx-ray for nds. Had problems with fatigue too. Cx-sprint on nds seems to hold up better for me (84-92kg). But no real data, just my case. But lacing does make a big big difference there. I'm a fan of 2:1 for the bw, as nds tension is a lot higher than on 1:1. Seems to give less fatigue issues, but no one solution is perfect for all riders
I would replace it, if another one breaks change all nds.
I don't really like cx-ray for nds. Had problems with fatigue too. Cx-sprint on nds seems to hold up better for me (84-92kg). But no real data, just my case. But lacing does make a big big difference there. I'm a fan of 2:1 for the bw, as nds tension is a lot higher than on 1:1. Seems to give less fatigue issues, but no one solution is perfect for all riders
They are 35mm deep LB rims. I was running them with tubes at 6,5bar. So I guess this happened when pressure in latex tubes dropped when I was away.
I do not have any way to measure how tight spokes are but when squeezing two of them at approximately half the distance from the hub to the rims I get approximately 10mm of deflection between them. (can’t measure how hard I squeeze but they do dig in my fingers and it hurts). The tire was on with 6,5 bar of pressure
The wheel was true, it’s true now beside the point where spoke is missing.
I guess they are laced radially on NDS and 2cross on DS. (I have pictures attached)
I also contacted LB support and they say that this happens rarely and they will send me few spare spokes so this one can be replaced and I’ll have some spare ones. But their replay seems like a generic one so I rather ask here.
I do not have any way to measure how tight spokes are but when squeezing two of them at approximately half the distance from the hub to the rims I get approximately 10mm of deflection between them. (can’t measure how hard I squeeze but they do dig in my fingers and it hurts). The tire was on with 6,5 bar of pressure
The wheel was true, it’s true now beside the point where spoke is missing.
I guess they are laced radially on NDS and 2cross on DS. (I have pictures attached)
I also contacted LB support and they say that this happens rarely and they will send me few spare spokes so this one can be replaced and I’ll have some spare ones. But their replay seems like a generic one so I rather ask here.
If you try to squeeze the spokes apart with your fingers where they cross, on a correctly tensioned wheel it should be more or less impossible to squeeze them apart on the drive side, and no more than a millimetre or two at most on the non-drive side. You don't say if you're squeezing the crossed spokes or the spokes on opposite sides of the wheel or what, but in any case, 10mm deflection is far too much - it would seem that the tension in all the spokes is too low.
The arrows are not showing direction of the force I'm applying just the two spokes I’m squeezing together. It's non drive side and they do not cross at all, they go straight from the hub to the rim on that side.
Additionally in front when I would try to pull them in the same manner they flex drastically less. Rear it's 24 spokes and front 20.
Additionally in front when I would try to pull them in the same manner they flex drastically less. Rear it's 24 spokes and front 20.
If you do attempt to replace the spoke and retrue the wheel youself with nothing else but a spoke key and a spoke holder I guess I'd try to do the following.
Try to get the NDS (left side) spokes to no less than ~70% of the front wheel spokes.
Try to get the DS (right side) spokes to no more than ~130% of the front wheel spokes.
The DS side is going to be the hardest because you can damage nipples if you play around too much at that kind of tension. The oil that was used building the wheels is most likely gone so you'll likely face seizing nipples. And lets not forget the problem of feeling spoke tension of crossed spokes so near the maximum tension limit. It's going to be a small nightmare untill you develop a hang for it. (I've built a few wheelsets and I still can't feel the difference between crossed spokes.)
If the nipples are aluminum you need to baby them. Be real gentle. They will break if the nipple key is crap, or you're doing too many adjustments, or the threads are seizing.
If you don't want to fix it yourself you can look for a wheelbuilder. It's a fairly quick job to tension everything up and true it, when you have the tools.
Try to get the NDS (left side) spokes to no less than ~70% of the front wheel spokes.
Try to get the DS (right side) spokes to no more than ~130% of the front wheel spokes.
The DS side is going to be the hardest because you can damage nipples if you play around too much at that kind of tension. The oil that was used building the wheels is most likely gone so you'll likely face seizing nipples. And lets not forget the problem of feeling spoke tension of crossed spokes so near the maximum tension limit. It's going to be a small nightmare untill you develop a hang for it. (I've built a few wheelsets and I still can't feel the difference between crossed spokes.)
If the nipples are aluminum you need to baby them. Be real gentle. They will break if the nipple key is crap, or you're doing too many adjustments, or the threads are seizing.
If you don't want to fix it yourself you can look for a wheelbuilder. It's a fairly quick job to tension everything up and true it, when you have the tools.
Don't even try it if you nipple wrench doesn't hold all 4 corners of the nipple!
I do not even have a spoke wrench so doing it by myself is not an option. I just wanted to know what my options are as there are no decent shop nearby. So a quick fix is out of the window as no one here stocks this spokes. Luckily I got a recommendation in the city nearby so hopefully this will be sorted by beginning of next week.
Thanks for your help.
Thanks for your help.
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bm0p700f
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35mm deep carbon rims are not that deep and I personally think cxrays are to thin for such a wheel with that spoke count. Cx sprints are a better bet. It could be fatigue ( it is fatigue) induced by a dodgey spoke,bad build or simply a wheel with not enough lateral and radial flex so that a spoke fatiguesand fails the way it has in the time it has.
You knew these possibilities and none of the answers above change that and frankly no one can give a form answer.
My take is relace with cx sprint of similar which is how the wheel should have been built in the first place. It how I would have done it, well I would not have bothered with a mid depth carbon clincher rim but that's another matter.
You knew these possibilities and none of the answers above change that and frankly no one can give a form answer.
My take is relace with cx sprint of similar which is how the wheel should have been built in the first place. It how I would have done it, well I would not have bothered with a mid depth carbon clincher rim but that's another matter.
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The wheel was true up until it failed, and it's been ridden for 9 months.
Could be a dodgy spoke, reused or something. The condition of the other spokes is hard to say.
Either that or the rim compresses like crazy. If that's the case simply adjust tensions with the tire on and pumped up and this could be avoided.
But then again if you want to be 100% sure it never happens again you hire a builder to replace the spokes.
Could be a dodgy spoke, reused or something. The condition of the other spokes is hard to say.
Either that or the rim compresses like crazy. If that's the case simply adjust tensions with the tire on and pumped up and this could be avoided.
But then again if you want to be 100% sure it never happens again you hire a builder to replace the spokes.
