chain keeps comin off

scottarm Posts: 119
edited June 2012 in Workshop
when changing from small crank cog to the large one the chain keeps coming off it seems to be coming off the side of the pedal

any advice how to fix? is the chain being pushed too far over when changing

its not happening everytime but it becoming more frequent



  • snoopsmydogg
    snoopsmydogg Posts: 1,110
    have you tried adjusting the derailleur?

    there is usually a couple of screws that stop them from going too far each way.
  • styxd
    styxd Posts: 3,234
    Yes, and in all honesty I dont really know how to fix it. It happens on my bike every few months. You can try adjusting the outer limit screw which stops the mech shifting as far, but then it probably wont shift onto the big ring at all.

    I usually just start again from scratch and completely reset my front mech. This sorts it but takes a good 25 minutes which is a bit annoying.
  • styxd
    styxd Posts: 3,234
    Also, what front mech is it?
  • scottarm
    scottarm Posts: 119
    tiagra I think, its the standard on the 2010 boardman road comp
  • styxd
    styxd Posts: 3,234
    Tiagra - fine.

    The SRAM one I had previous to my shimano seemed to suffer this problem alot more.
  • smidsy
    smidsy Posts: 5,273
    If the front mech is adjusted correctly it should be OK. If it is alright most of the time it could be something else.

    What technique do you use when changing? Ease of the power slightly and you may find it helps.

    What condition are the chainrings in? Any unusual or significant wear?
    Yellow is the new Black.