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Front mech problem

MrSquishyMrSquishy Posts: 277
in General Chat
My chain came off yesterday and now for some reason my front mech won't move the chain up on to the large chainring - it moves the chain up but then springs back down straight away. Anyone got any ideas what's happened and how I can fix it? I don't really want to take it to the LBS unless necessary, and I should really be able to fix stuff like this.

Comments

  • risris Posts: 1,002
    is it making the usual indexing noise at the shifters? has the limiting screw been knocked at all?

    sorry, front mechs aren't something i know very well so i'm probably not asking useful or helpful questions.
  • MrSquishyMrSquishy Posts: 277
    It still clicks in the same way that it did when it was working properly, so I think the indexing it still OK.
  • huwdhuwd Posts: 228
    With the rear wheel off the ground - if you push onto the big cog and spin the pedals to get the change to engage, are you able to push the mech any further away from the seatpost (to check the top end stop adjustment)

    Sounds a bit like the cable might have slipped or the mech has been dragged out of alignment when the chain came off.
  • ShaggyShaggy Posts: 140
    Is the cage- (chain guide) still parallel with the cogs? If it is a clamp on (clamped around the tube and tightened with an allen bolt) it may have been pulled around.

    Ade
  • BmanBman Posts: 442
    As shaggy said, check the cage for alignment (should be parallel to the chain). Assuming the limiters are set ok, its just the cable tension that needs to be adjusted. When the front mech is in its lowest tension, the spring will pull it towards the frame, ideally so that the chain is on the small ring. When you change ring, the tension in the cable pulls the mech out and changes gear, so by tightening the cable a bit, it should pull out a bit further and move it up a ring. And that where the outer limiter comes in and restricts the cage from letting the chain go over the outer edge. I think.
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