Rear mech problem

Hi all,

The rear mech on my son's Hoy 20" bike seems to have gone. It started by not being able to move the chain up to the first gear. Now it won't move it up or down at all.

Does anyone know what might be wrong and if it's a simple fix? If it's more complicated, do you know roughly how much it should cost to get it fixed by a LBS? My LBS is currently shut and the nearest one that's open, let's just say I'd like to have an idea of what it should cost.

Many thanks in advance!

Josh

Comments

  • The Rookie
    The Rookie Posts: 27,812
    Maybe post in workshop and not buying....

    Can you move the mech by hand? (in towards first gear or out towards top?)

    What has been touched AT ALL, screws, cable etc?

    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.
  • joah
    joah Posts: 28
    Sorry yes, should have done.

    I can push it up to slacken the chain, but not in our out. To my knowledge no screws or cables were touched. The bike fell over on its side a few times so maybe it got knocked?
  • The Rookie
    The Rookie Posts: 27,812
    Sounds like the rear mech or hanger got bent/damaged, you should be able to push it in closer to the wheel (the way it would move as the cable is pulled), the only thing that would stop that is if someone has screwed in the low stop (there are two limit screws, H and L), the low stop stops it accidentally going into the wheel, if that has been screwed in it will prevent selection of the lowest gears. the H stop prevents it moving the chain off the smallest/highest gear into the frame.
    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.
  • joah
    joah Posts: 28
    Thanks, I'll try pushing it closer. No-one has touched the screws that I'm aware of.
  • photonic69
    photonic69 Posts: 2,341
    Hi. Try this - remove rear wheel so you can release chain from the rear cassette.

    Push area marked with Red away from you. It should move easily but against the tension of the springs. If it seems stiff then put some oil on the areas marked with Green and work backwards and forwards until it eases.

    The derailleur should move across the whole distance of the width of the rear cassette.

    If it moves easily in the first instance then the problem probably lies with the cable which may need replacing.

    Hope this helps?



    Sometimes. Maybe. Possibly.

  • swod1
    swod1 Posts: 1,639
    a few videos you can watch on youtube to help with this, it could be a number of things

    bent derailleur hanger
    cable tension/gear indexing
    limit screws

    Is the bike recently new, after a while you sometimes need to adjust the gear cable tension as the cable stretches with use or isn't setup correctly
  • joah
    joah Posts: 28
    edited May 2020
    Sorry for the delay in replying - thanks a lot for all your help guys. As it happened I had to go to the LBS anyway and it was a quick job for them to fix. But worth knowing for next time!

    Josh