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Mole grips to twist Ultegra 6800 medium cage back to shape and stop chain dropping off jockey

yertezyertez Posts: 80
in Workshop
My 2015 Canyon Ultimate with Ultegra started chucking the chain off the lower jockey wheel after an unplanned section of Wiltshire strada bianche (ie unpaved road).

The chain would always come off to the wheel side of the jockey wheel, and only when on the inner chain ring and in the mid range on the cassette.

I replaced the 30K old jockey wheels, didn't fix it. Replaced the cheapo chain with an Ultegra one - made it better but not totally fixed.

Had a long look at the rear cage and figured it must be twisted - maybe copped a stone on the off-road ?

So by very carefully gripping the upper jockey in a mole grip (and an old sock), and using a pipe wrench over the lower jockey wheel I twisted the cage to point the jockey wheel more into the frame.

Did a 40K ride and problem seems to have gone at last...

The medium cages do allow a 32T but are a little more fragile than the short.

Posts

  • itboffinitboffin Posts: 20,050
    yikes! that's a bit brutal what you need is a mech alignment tool or take it to your LBS to have them do it, keep the mole grips away from the bike or you could find yourself with a snapped mech hanger and even the rear mech into your wheel where it will do damage and could lead to a crash too boot.
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  • darkhairedlorddarkhairedlord Posts: 7,179
    Just buy a new rd and hanger.
  • lesfirthlesfirth Posts: 1,370
    Well done Yertez! You have fixed the problem. I am not sure that I would have done that but like me you probably don't have a LBS. ( by choice not geography). They are places you are best keeping away from.
  • veronese68veronese68 Posts: 26,302 Lives Here
    I would have taken the thing off and stripped it before straightening the plates separately, but if it worked...
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  • darkhairedlorddarkhairedlord Posts: 7,179
    Make sure all the moving parts, parallelogram frame, pins, etc are all true, these can become buckled and induce play and poor alignment. Especially after a straightening! If it's not perfect just buy a new RD, 105 will do if you're not feeling spendy.
  • david37david37 Posts: 1,313
    wot dark lord said or second hand off the bay.
  • yertezyertez Posts: 80
    Forgot to mention I also tried a brand new rear hanger as well which didn't fix it.

    Next stop was a new RD, so this was worth a try first.
    Good tip re the 105.
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