Ultegra Di2 rear derailleur indexing

Crashs2k
Crashs2k Posts: 78
edited September 2015 in Workshop
Having a problem with Ultegra 6870 Di2 rear derailleur indexing. Will only shift down to the smallest cog if I microindex it all the way over to the outside of the bike (16 positions). Don't think this is right - any suggestions to probable cause?

Frame has never been crashed and no washer behind cassette. Only thing I can think of is a bent derailleur hanger perhaps?

Comments

  • dgunthor
    dgunthor Posts: 644
    is the limit screw set ok?
  • DKay
    DKay Posts: 1,652
    Sounds like the mech has not been set up correctly from the beginning. I'd set the micro-adjust back to the middle and start setting up the mech from scratch again.
    N
    N+1
  • Crashs2k
    Crashs2k Posts: 78
    Tried both. Any other suggestions?
  • big_p
    big_p Posts: 565
    Sounds like the hanger is bent.
  • dgunthor
    dgunthor Posts: 644
    looking at the mech from behind should give a fair indication of whether the hanger is bent i.e. mech cage should be vertical
  • CiB
    CiB Posts: 6,098
    Did you do start the indexing with the mech in roughly the central plane? It has 31 micro-steps in indexing mode so if e.g. you've already swallowed most of them up by being in micro-click pos 1 (instead of say 13) its got nowhere to go and may be one gear higher or lower than it thinks it is. Go back to basics - in indexing mode go all the way in one direction, then step back 15 steps to make it central, drop out of index mode then check that it changes smoothly into the lowest & highest gears, then index (from a middle gear) - it shouldn't need more than half a dozen micro-steps to be right, and then you can check the limit screws.
  • Crashs2k
    Crashs2k Posts: 78
    Thanks for all the replies and suggestions. I have checked it is in the middle of it's adjustment and when it is it doesn't drop into the smallest sprocket. It only changes when I set the micro adjustment all the way over to the outside of the bike.

    Looks like I need to take it to my lbs and get them to check hanger alignment.

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