Rear Derailleur

kennygalbraith Posts: 101
edited May 2013 in The workshop

This cycling malarky is costing a fortune! :D

My bike is a specialized crosstrail sport hybrid bike with around 3000 miles done in a year.

My rear derailleur is seizing up and I'd like to either overhaul it or buy an new one, and advice?

My front one isn't great either, I think the winter has taken its toll on it.

Easy/hard job? Worth doing or buy a new one? I don't want to spend much as my freehub needs replaced and my headset is worn(apparently)

Shimano Acera RD-M390 9-Speed Rear Derailleur is what's on the bike.



  • sharky1029
    sharky1029 Posts: 188
    The rear derailleur probably just needs a good clean and maybe re indexing. To clean it thoroughly, you have to remove the chain, clean any crud of it especially from the pivots and the spring using a toothbrush and some degreaser/ muc off/ white spirit or similar and then remove the jockey wheels and add some thick lube or light grease on the jockey wheel bushings. It may be worth taking it to a shop and ask for a service and they should be able to do it all but it will cost about £40 otherwise have a look on youtube for some video turorials including a few from bike radar on indexing and cleaning.
  • cheers for the reply, I've already gave it a clean using muc off/degreaser etc with a toothbrush. I took it to the LBS today and they spotted it was seizing up but they said it would cheaper to buy a new one...I like fixing things though :)
  • gbsahne001
    gbsahne001 Posts: 1,973
    The original dérailleur on the hybrid lasted 15 years and probably had done 20,000 miles. Sounds more like issues with keeping your cables, dérailleur and chain clean.
  • The Rookie
    The Rookie Posts: 27,812
    What does seizing up mean in reality?

    The jockey wheels aren't turning, or it's not moving freely sideways on the pivots giving poor gear changes, if so is it up or down changes?

    May just need a good spray with a decent penetraing oil and (with the wheel out) moving back and forth to free the pivots off, then some lube applying to protect them, having said that, Acera is fairly low rent and a better mech will last longer and be lighter with better Jockey wheels, Deore would be a go to replacement.
    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.
  • desweller
    desweller Posts: 5,175
    I like to submerge el cheapo seized mechs in warm, clean engine oil and agitate them for a bit. Does a fine job of transporting the rubbish out of the inaccessible places and gets plenty of oil into the bearings.
    - - - - - - - - - -
    On Strava.{/url}
  • thanks for the advice, I'll give soaking it in some degreaser and oil at the weekend :)
  • thanks for the advise, I took the derailleur off at the weekend and used bikehut degreaser to get any crud off it. Its working much better, I couldn't get the barrel adjuster to work but i'm going to the LBS today anyway so i'll ask them.
    Thanks again for the advise! :D:D:D:D:D:D