Broken Spoke ................ any ideas why?

[R.P.M]

Hi guys,

Had a bad day last saturday, aside from loosing my chain (yep thats right, couldnt find it anywhere!) I broke a spoke in my rear wheel on the disc side.

Why would this happen?
Would it be related to the fact that I put a 203mm rotor on the wheel only two rides before? Has the increase in leverage due to the increased rotor size caused a spoke to snap at the hub end?

What are your thoughts people, as if this is the case I think i will swap the rotor back to a smaller dia, instead of keep snapping spokes!

thanks in advance
rpm

[Parrot of Doom]

Shit happens. Spokes snap. Metal fatigue, possibly over-tensioning.

It could very well be because of the new disc, but tbh I had spokes snapping on my road bike 15 years ago and that uses caliper brakes.

If you have a spoke key its quite alright to retension the surrounding spokes. I've cycled for months on a wheel with 2 broken spokes.

Edited by Parrot of Doom on Tuesday 6th November 21:49

[WildCards]

How old is the wheel? Was it factory built or hand built? Had you put it under a rather large load recently?

[R.P.M]

WildCards said:

How old is the wheel? Was it factory built or hand built? Had you put it under a rather large load recently?

wheel is from 11 month old stumpy comp. Hub is shim m525 with std 2mm spokes, laced to a dt swis x4.5 rim.

done approx 500 miles in all conditions and done no more than 3ft jumps/drops. just the normal trail riding really.

[R.P.M]

Parrot of Doom said:

Shit happens. Spokes snap. Metal fatigue, possibly over-tensioning.

It could very well be because of the new disc, but tbh I had spokes snapping on my road bike 15 years ago and that uses caliper brakes.

If you have a spoke key its quite alright to retension the surrounding spokes. I've cycled for months on a wheel with 2 broken spokes.

Edited by Parrot of Doom on Tuesday 6th November 21:49

one random over tensioned spoke was thought about.

RPM

Edited by R.P.M on Tuesday 6th November 22:31

[WildCards]

R.P.M said:

WildCards said:

How old is the wheel? Was it factory built or hand built? Had you put it under a rather large load recently?

wheel is from 11 month old stumpy comp. Hub is shim m525 with std 2mm spokes, laced to a dt swis x4.5 rim.

done approx 500 miles in all conditions and done no more than 3ft jumps/drops. just the normal trail riding really.

Meh! that was all I could think of and it's obviously a decent wheel. It could be the disc, but i'd lean more towards sods law. Do what PoD said or get it fixed, either way it shouldn't be too expensive. If it happens again of course then you may have a problem.

[Trooper2]

General rule of thumb is, if you break 3 spokes on any one wheel, get it rebuilt.

[Cabinet Enforcer]

Almost certainly a fatigue failure, apart from getting hit by rocks, that is why spokes snap. The bigger rotor might have made the problem worse, but the spoke would have snapped eventually. It's fairly likely that you will continue snapping spokes, it may be cheaper to get the wheel rebuilt sooner rather than later, if you experience any more snapped spokes in the near future then don't just keep getting them replaced as it will never solve the problem.

You don't really say specifically but I get the impression that the wheel is the one that came with the bike out of the factory, in which case it will probably have been machine built with plain gauge spokes which is not a recipe for long lasting wheels, if you end up getting it rebuilt then get double butted spokes, they are much more resistant to fatigue issues.

[R.P.M]

thanks for all those replies.

Have had the broken spoke replaced, but am think on replacing the wheel with a hope pro11 hub laced to a dtswiss xc4.2 with double butted spokes.

Now do you recommend 32 or 36 hole, am thinking of going with the extra 4 spokes as this must offer more strength and stiffness for not much more weight?

cheers
RPM

[Parrot of Doom]

More spokes also equals more air resistance. Not much, but enough.

Broken spokes are easier to replace if your hub is like this:



Basically means you don't have to faff around removing the cassette.