Chain coming off the top ring

gotwood25
gotwood25 Posts: 314
edited July 2013 in The workshop
Wanted a bit of advice before I start spending money.

Noticed recently when I am in top gear, out of the saddle with my foot in the 2-4 o'clock positions the chain is coming over the top of the crank. Does this sound like a worn chainset? Its probably done just over 2000 miles or is there anything else I can adjust before I upgrade?

Cheers

Comments

  • t4tomo
    t4tomo Posts: 2,643
    sound like the limit screw on your front deraileur needs a tweak inwards.

    have a quick google /look on you tube if youb are unsure which screw does which.
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  • The Rookie
    The Rookie Posts: 27,812
    +potato
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • gotwood25
    gotwood25 Posts: 314
    Cheers t4tomo, will give those a tweak.

    Beginner, don't quite get it but I hope your other 11549 posts are just as insightful.
  • The Rookie
    The Rookie Posts: 27,812
    It's seconding the post above mine...... common forum language.....
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • wandsworth
    wandsworth Posts: 354
    t4tomo is surely correct that adjusting a limit screw is the answer, but I'm here to tell you that tweaking the front mech is the door to a world of pain. I'll spare you the gruesome details of the hours I spent yesterday figuring out which screw is L and which is H, then getting involved in adjusting the cable tension. There are lots of videos giving advice on YouTube, but they're not all consistent. (See if you can find phlegm guy.)

    Turns out that simple though it looks, front mech action is a complex interaction between the H and L screws (clockwise? anticlockwise?), cable tension and the alignment of the planets. I ended up admitting defeat and taking it into the LBS this morning. My advice would be to make very small (1/8 turn) adjustments of the relevant screw and remembering where you started so you can go back to that state if necessary. Then take it to the LBS.
    Shut up, knees!

    Various Boardmans, a Focus, a Cannondale and an ancient Trek.
  • supersonic
    supersonic Posts: 82,708
    You only have to adjust cable tension when tweaking the H screw if the mech cannot reach the limit. In this case it needs screwing in to prevent derailment, so no cable tweaking necessary (assuming is indexed right elsewhere).
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  • The Rookie
    The Rookie Posts: 27,812
    Blimey and there I was thinking that tweaking the front mech indexing was just a 5 minute job.......
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • wandsworth
    wandsworth Posts: 354
    supersonic wrote:
    You only have to adjust cable tension when tweaking the H screw if the mech cannot reach the limit. In this case it needs screwing in to prevent derailment, so no cable tweaking necessary (assuming is indexed right elsewhere).

    Thanks. Wish I'd known that yesterday ...

    What can cause a front mech to go out of alignment like that? Assuming it has not been knocked and bent out of shape.
    Shut up, knees!

    Various Boardmans, a Focus, a Cannondale and an ancient Trek.
  • The Rookie
    The Rookie Posts: 27,812
    Who said it was out of alignment? Adjustement and alignment are different things (alignement you set with the clamp round the seat tube, or not at all for direct mount!)

    Cables stretch, pawls and rachets wear, that you adjust with the cable tension, the H or L screw may not be set right and masked by whatever the tension is, adjust cable tension and you could expose an issue with the H or L screw setting.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Initialised
    Initialised Posts: 3,047
    The Beginner wrote:
    Blimey and there I was thinking that tweaking the front mech indexing was just a 5 minute job.......
    It is a 5 min job, adjust the high and low stop and possibly the derailer angle then put it in the smallest ring and take u any cable slack and repeat making sure it shifts properly.
    I used to just ride my bike to work but now I find myself going out looking for bigger and bigger hills.
  • The Rookie
    The Rookie Posts: 27,812
    Sorry that my sarcasm wasn't obvious enough for you....
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

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