Need help with my mountain bike rear gear selector please

edited 23 May 2020 at 9:32AM in Public Transport & Cycling
5 replies 251 views
ferryferry Forumite
1.9K Posts
Part of the Furniture 500 Posts
edited 23 May 2020 at 9:32AM in Public Transport & Cycling
Hi , I have dug out my old Peugeot Origin mountain bike from the back of the shed and it has a damaged Shimano rear gear selector ( derailleur)?
I know nothing about bikes - Are these generally hard to change and how would I go about selecting the correct parts to replace it please?

F x


  • wongataawongataa Forumite
    2.3K Posts
    Eighth Anniversary 1,000 Posts Name Dropper
    They aren't hard to change.  To change one you will need suitable size hex keys/screwdrivers/spanners for the various fixings and a chain breaker tool to take the chain off.
    If you want a replacement one you will need to source a new one that is compatible with the number of cogs on the rear wheel and your shift levers on the handlebar.
  • inspectorperezinspectorperez Forumite
    486 Posts
    100 Posts First Anniversary Name Dropper
    Not hard to change if you know what you are doing. I do many jobs on my own bikes, but I wouldn't tackle this job. Do you not have a mobile bike mechanic in your area? Our local "Nextdoor" community website is very useful in locating such people so it might be worth joining up for your own area and simply placing a request online. The main man in my own area works within the Social Distancing rules and is extremely competent and inexpensive. He will also source any needed components.
  • alembicbassmanalembicbassman Forumite
    91 Posts
    Part of the Furniture 10 Posts Combo Breaker
    If the rear derailleur has been knocked it's likely bent the hanger it is screwed onto. On steel bikes you can usually bend this back into place, but on aluminium bikes it sometimes snaps off. Many aluminium bikes have replaceable mech hangers, but they're quite expensive for what they are £15 ish. Shimano rear derailleurs (7 Speed Tourney) Start at about £12. A new derailleur will only work if correctly aligned, which may require a visit to a bike repairer.
    The video below gives you a good idea.
  • vitaweatvitaweat Forumite
    331 Posts
    100 Posts Name Dropper
    Google "Sheldon Brown".  The website is really old and clunky but it is an amazing resource for cycle maintenance. 
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