compact chainset issues

Barney24
Barney24 Posts: 9
edited September 2010 in Road beginners
HI,

I just bought a sram rival compact chainset with GXP bottom bracket. I have a 68mm BB shell and fitted itwithout spacers abut when in the inner chain ring (34T) and outer sprockets 12 -14 the chain is trying to shift to the outer chain ring (50T) without any pressure off the front derailleur.

I then tried putting spacers in and the cranset doesn't tighten up properly.

Does anyone have any suggestions?

Thanks

Tom

Comments

  • softlad
    softlad Posts: 3,513
    you shouldn't be running that much crossover from front to rear. There is probably nothing wrong with anything you have fitted - but you need to be a bit more careful with your choices of gear combination...
  • Barney24
    Barney24 Posts: 9
    Hi,

    Thanks for reply, yeah i know about cross over but even so the chain shouldn't be jumping and trying to shift onto the larger chainring.

    No worries I'll pop to the local bike shop and ask was more a quesiton about whether spacers should be used?

    Tom
  • softlad
    softlad Posts: 3,513
    the spacers are not needed on a road frame. Leaving aside the issue that you shouldn't be in that gear anyway, it might just be a matter of adjusting the limit screws or the cable tension. There isn't really much going on with the front mech that can't be sorted by attending to at least one of the above...
  • rake
    rake Posts: 3,204
    A. dont run that combination.
    B. dont use spacers. its a floating bearing one side (the left one sets the chainline only.. if you space it out too much the bearings will be loaded and not tighten propperly .the right bearing needs to be free to float on the crank shaft. no preload. this is what makes it different from shimano style crankshafts.


    )

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