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Chain Coming Off...

NuggsNuggs Posts: 1,804
edited August 2008 in Workshop
Hi Gang

In the last 50 miles my chain has come off 4 times when shifting the front dérailleur - twice over the top and twice into the frame.

Until yesterday, it hadn't come off for ages and I've not adjusted anything or (knowingly) knocked it.

I'm wondering whether it would be unwise to start fiddling on with the H and L screws, particularly as for hundreds of other shifts they've been working fine. The dérailleur is almost touching the chain in the lowest gear so I suspect there's not much inward adjustment to be had in any case.

Any ideas? Am I just being ham-fisted with my changes (all derailments have happened when I've been pushing hard) or is it time to get busy with the spanners (again)?

Thanks guys - your help is, as ever, appreciated :)


  • chuckcorkchuckcork Posts: 1,471
    The H and L are there for a reason, the chain coming off as often as that suggests that the adjustment is both too high and too low. If you haven't had a problem before it is likely there is a cable stretch issue as well, which is where barrel adjusters come into use.

    Spanners usually not required, normally a screwdriver.

    If your not sure I recommend a book, like Zinn ... 1884737706 , and to make it easier something like a home repair stand e.g. like one of these ... &x=10&y=11 which will in any event make maintaining and cleaning your bike way easier.

    With both you can set your bike up on the stand and adjust to suit while spinning cranks, changing gears etc to see how the adjustment is going, before doing a final fine adjustment on the road.
    'Twas Mulga Bill, from Eaglehawk, that caught the cycling craze....
  • NuggsNuggs Posts: 1,804

    I spent hours setting it all up a couple of months ago and so I have a fair idea of how things work.

    What I'm more concerned about is whether the H and L screws are the likely problem here, given the fact that on the whole the chain's behaving itself?
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