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Spokes snapping at elbow

jds_1981jds_1981 Posts: 1,858
edited March 2017 in Commuting chat
Okay,

Not that unusual, my rear drive side spokes are now snapping quite regularly and one none drive side has gone. Time to rebuild.
I noticed after unscrewing the second spoke (first one popped as i started unscrewing it) that the inside of the elbow was actually slightly worn.
These wheels have been kept under reasonable maintenance although the ride in is quite rough and wet or dusty. Normal wear then?
As an aside, the rims are cheap mach1 820. Can't find a recommended tension for the spokes so what is a good rule of thumb?
FCN 9 || FCN 5

Posts

  • RhodrichRhodrich Posts: 870
    Generally, spokes, when they do snap, more often than not snap at the elbow, which is the area of highest stress.

    Once more than one or two go, you're right to say that the wheel should be replaced/rebuilt.

    If the spokes start snapping before the rim is worn out, this usually points to either poor quality spokes, or a poorly built wheel, with tension that is too low or uneven. Spokes shouldn't wear on the elbow, as they should always be in tension. It's when the tension is so low that they go out of tension as the wheel is loaded when you get big problems. It's rarely a problem with the rim.

    If you decide to rebuild the wheel from scratch, I'd recommend reading 'The bicycle wheel' by Jobst Brandt, which should tell you all you need to about how to build a strong, reliable wheel.
    1938 Hobbs Tandem
    1956 Carlton Flyer Path/Track
    1960 Mercian Superlight Track
    1974 Pete Luxton Path/Track*
    1978 Dawes Chevron Fixed
    1980 Harry Hall
    1986 Dawes Galaxy
    1988 Jack Taylor Tourer
    1988 Pearson
    1989 Condor
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    *Currently on this
  • jds_1981jds_1981 Posts: 1,858
    Well, they aren't great quality wheels but I have kept them reasonably tensioned. They have however done about 10k miles on canal track, ridden fairly hard.

    As they're disc brakes I suspect it is fairly natural for the spokes to go before wear on the rim ;)

    The few I've looked at all seem to have a similar amount of wear so I don't think it is due to a few being under tightened.
    FCN 9 || FCN 5
  • Was it drive side or non that was worn like that? If drive side, it could be that your limit screws were off and the chain got trapped between cassette and spokes - that's a pretty quick way to kill spokes.
  • jds_1981jds_1981 Posts: 1,858
    Was it drive side or non that was worn like that? If drive side, it could be that your limit screws were off and the chain got trapped between cassette and spokes - that's a pretty quick way to kill spokes.

    Both, it's on the inside of the elbow only. Will see if I can take some pictures of a few.
    FCN 9 || FCN 5
  • RhodrichRhodrich Posts: 870
    10k miles is nothing for a well built wheel. Once built, they shouldn't need touching. The fact that you've had to 'keep them reasonably tensioned' suggests to me that they were badly built to start with. If they've gone out of tension through normal riding, there is wear on the elbows, and spokes are snapping, the tension must have been too low to start with. Not uncommon with cheap machine built wheels.
    1938 Hobbs Tandem
    1956 Carlton Flyer Path/Track
    1960 Mercian Superlight Track
    1974 Pete Luxton Path/Track*
    1978 Dawes Chevron Fixed
    1980 Harry Hall
    1986 Dawes Galaxy
    1988 Jack Taylor Tourer
    1988 Pearson
    1989 Condor
    1993 Dawes Hybrid
    *Currently on this
  • jds_1981 wrote:
    Was it drive side or non that was worn like that? If drive side, it could be that your limit screws were off and the chain got trapped between cassette and spokes - that's a pretty quick way to kill spokes.

    Both, it's on the inside of the elbow only. Will see if I can take some pictures of a few.

    In which case I suspect they were cheap, crappy spokes and probably weren't quite tight enough either.
  • itboffinitboffin Posts: 19,683
    damn you and your spoke thread, my commuter started making a horrible noise yesterday, i've worked out its the rear wheel but nothing looks visually wrong, one spoke has more movement and sounds dead

    if its loose then wouldnt the wheel be out of true, shimano RS10 so low spoke count
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  • jds_1981jds_1981 Posts: 1,858
    Wheel was cheap but reasonably tensioned.

    Heh, my first indication of trouble was the free week became very sticky. After the ride realised a spoke was poking into the cassette, but would spring free after it bent so far
    FCN 9 || FCN 5
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