Forum home Mountain biking forum MTB workshop & tech

derailleur hanger

luvrlyjuberlyluvrlyjuberly Posts: 5
edited October 2017 in MTB workshop & tech
I'm trying to fix up a bike that needed a new rear derailleur - I fitted it and the derailleur wheel touches the spokes of the back wheel when the chain is on the biggest cog, I've tried everything with no luck. I had a look at the derailleur hanger and it is bent -so to the question - Is it supposed to be shaped this way or should it be pretty flat? And could this be the cause of my problem?
938ce9620412623.jpg 05ebd6620412863.jpg

Posts

  • mattyfezmattyfez Posts: 638
    Normally are flat, but it would have to be very bent to hit the spokes, or do you mean the derailleur hits the spokes when fitted?

    But it looks bent to me.
  • yes the derailleur cage touches the spokes -

    I was not sure if that was the correct shape for the hanger or if it had bent when the original derailleur snapped.
    Thanks for the reply.

    I've ordered a new one anyway - if the spoke problem still occurs it's off to the LBS as I'm baffled!
  • cooldadcooldad Posts: 32,601
    Very bent.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Thanks well fingers crossed the new hanger solves my problem!
  • dgmoosedgmoose Posts: 16
    This type of hanger problem is very easy to fix.

    You do not need to remove the hanger from the frame.

    You just need to bolt your rear wheel tightly in place and screw in an M10 threaded bar (eg a rear Shimano cup and cone axle). Then, slowly bend the hanger using the M10 bar until it is parallel (eyeball from above and from the side) to the wheel axle.

    It does not matter if the hanger still appears bent afterwards, as long as the hanger hole is parallel to the wheel axle, it will work.
  • cooldadcooldad Posts: 32,601
    Easy to straighten, but aluminium doesn't like being bent and straightened, so could get weakened, will fail catastrophically at the worst time and destroy mech, wheel, and kill you if you fall off.*

    *This may not actually happen in all cases.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • mattyfezmattyfez Posts: 638
    I've snapped a hanger before, derailleur got wrecked as it fell into the wheel and it also took out about 5 spokes and twisted the chain.

    So my shopping list was
    New mech
    New hanger
    New chain
    Some spokes and a wheel true

    Generally speaking I'd advise just to replace a hangar rather than straighten it.
Sign In or Register to comment.