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  1. #1
    mtbr member
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    Aug 2004
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    Rohloff Ratio Question

    I have an XTR M960 crankset with a 32T middle ring and 44T big ring, I am a little unsure which Rohloff cog I can use with the chainrings. I think if I use my 32T ring I would need a 13T cog to comply with Rohloffs permissible sprocket ratio. If I did use a 13T cog I think it would mess up my chain line. If I use my 44T big ring I could use a 17T cog which would work but again I don't know if my chain line would be off. Anyway if you have any input on the matter it would be greatly appreciated, I really don't want to buy a new crankset. Thanks.

  2. #2
    Music & Bikes
    Reputation: fokof's Avatar
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    Apr 2006
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    937
    The Speedhub chainline is for the external plate.

    Maybe you can find a 40 or a 42 if it exists.....

    You also can go a little lower than what Rohloff permits without destroying it.
    "There is a big difference between kneeling down and bending over" -FZ

  3. #3
    1*14*29*2.1 & 1*1*29*2.4
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    yes, the outer ring is the correct line. A 17t rear is no problem and should wear a little better hopefully than the standard 16. If you are getting a new set, see if the supplier can substitute the 16 with a 17 as they aren't cheap sprockets.

  4. #4
    On MTBR hiatus :(
    Reputation: Speedub.Nate's Avatar
    Join Date
    Dec 2003
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    9,145
    Also worth noting larger rings / cogs result in greater drivetrain efficiency. Probably not enough to notice, but definitely enough to measure.

    Question is, does the (also minor) weight savings and ground clearance of smaller rings/cogs outweigh the increase in efficiency?

    To maximize drivetrain life, a 40T Surly stainless steel chainring ($30) plus a 17T Rohloff cog will last a good long while.
    speedub.nate
    MTBR Hiatus UFN

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