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First time on any bike that I have broken a spoke. It instantly deformed the wheel making the bike un-rideable. From what I've read a single broken spoke should not do this, so anyone know what's going on here?

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    What kind of bike? Front or back wheel? How many spokes? Have you hit anything lately?
    – andy256
    Oct 10 '15 at 5:36
  • scott sportster 50, rear wheel original wheel about 5 years old. i was on the road when it happened - large bang. just surprised when so many threads say one spoke is no issue, maybe i hit a rock
    – Dagon
    Oct 10 '15 at 5:49
  • How many spokes on the rear wheel? Could be 32 or 36 for a "normal" bike, but could be fewer if its sporty. The more spokes you have, the less work each spoke does. In the extreme wheels that have 20 down to 8 spokes, each one has to deal with a large area of rim, so 1/20 going will warp the wheel more than 1/36 spokes.
    – Criggie
    Oct 10 '15 at 7:44
  • Kind of bike = hybrid. Make = Scott. Model = Sportster 50. Number of spokes?
    – andy256
    Oct 10 '15 at 8:47
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    It's not at all unusual for a single broken spoke to cause a wheel to warp badly enough that it causes the brakes to drag. I've had this happen on 36-spoke wheels, and it's even more likely as spoke count decreases. A temporary "limp home" fix is either to open the brake caliper (being aware that you will then have no brakes on that wheel) or release tension from the two adjacent spokes (using a spoke wrench). There are also emergency spoke kits made, containing a cable "spoke" that can be used to replace the broken one. Oct 10 '15 at 12:15
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It sounds like that spoke was carrying a lot of tension by itself. Perhaps because the wheel had been damaged previously. When the spoke failed, the nearby spokes on the side with the broken spoke weren't tight enough (or plentiful enough) to support the rim and it was pulled into the warped shape.

It could be that the way you were riding at the moment (if you were maneuvering or climbing – anything that would put an unbalanced load on the wheel) may have contributed to the sudden change of shape, or there may have been stresses in the spokes and/or rim that caused it to warp when the spoke broke. Do you know anything about the history of the wheel that might help us sort it out?

If the wheel is well built with enough spokes and a rim that is appropriate for the use and the spokes are sufficiently and evenly tensioned the failure of a single spoke shouldn't be a huge event – you might find that the rim is dragging on the brakes a bit, but I wouldn't expect anything that you couldn't patch together well enough to ride home (assuming non-extreme conditions).

The caveat is that I tend to be pretty conservative – wide rims, lots of spokes, and I'm fussy about spoke tension. So I don't know too much about spoke failures on light weight wheels with a minimal spoke count. There I would expect the failure of a single spoke to be more of a problem.

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  • thanks, there's no alternate "answer" but this was very helpful.
    – Dagon
    Oct 10 '15 at 20:27
  • You're welcome, I'd be very interested to hear what you discover if you learn more about what happened.
    – dlu
    Oct 10 '15 at 21:24

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