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  1. #1
    mtbr member
    Join Date
    Oct 2013

    Bonking ... not feelin' well Jet 9 RDO 2013 - Shimano XTR M985 crank 40/28 compatibility

    Hi Niners,

    I've just bought a Black & White 2013 Niner Jet 9 RDO.
    It came with a M785 XT Crank.
    I've decided to buy a XTR M985 40/28 crank and I did.

    Only after the purchased I saw in the following link on the Niner website (
    "Shimano XTR recommended 2X chainrings: 26/38T. We do not recommend the use of 40T (48.8mm chain line) cranks because the large chainring may contact the frame".

    Now what exactly does that mean?
    1. Can I use the M985 with 28/40?
    2. If not, can I just replace the 40T chainring with 38T one?
    3. Is there a M985 38T chainring?
    4. If not, do I need to replace both chainrings or replace the crank to M980 altogether?


  2. #2
    Reputation: have2ride2day's Avatar
    Join Date
    Nov 2009
    It says "the large chainring may contact the frame". So, if it was me, I would try it before I did anything else.
    Addicted to the Classifieds

  3. #3
    mtbr member
    Join Date
    May 2012
    That crankset is actually different chainline compared to the XT crank listed. I imagine that the chainrings will make contact with the frame like they say it does, although I have not personally tried it. I think the only chainring options for your crankset are 40T and 42T, I have not seen a 38T for the 88MM BCD that it uses. I see that the XTR niner build kits come with the raceface carbon crankset, that might be a good place to start.
    Quote Originally Posted by meltingfeather View Post
    If I told you I saw a unicorn ****ing a leprechaun trail side, you'd probably be suspicious.

  4. #4
    mtbr member
    Reputation: Radical Rad's Avatar
    Join Date
    Sep 2009
    So did the 40/28 work? Or what did you do?

  5. #5
    mtbr member
    Join Date
    Oct 2013
    no luck with the M985.
    i changed to the M980 triple crank set up with 2 chainrings 38/26.
    sorry for the bad news...

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