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  1. #1
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    Dum XTR crankset question

    Hello. So I just installed the Shimano FC-M970 crankset - and that all went swimmingly.

    My question is about the adjustment nut (which is turned with the TL-FC17). I can't really figure out what it (the adjustment nut) does.

    The documentation says to turn the adjustment nut in order to adjust the play. What does "play" mean in this context? Sorry, I'm a mechanical noob!

    Also should there be any gaps between the adjustment nut and the crank arm side, or between the adjustment nut and the bottom bracket side?

    Cheers!

  2. #2
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    The adjustment nut is supposed to be turned to eliminate the gap between the crank and the BB bearing. There may well be a gap until you do wind that nut in toward the BB shell.
    I'm a member of NSMBA and IMBA Canada

  3. #3
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    the play they're talking about is the side-to-side play of the crankset inside the bottom bracket.

    with the adjustment ring flush against the crank arm, you will have lots of play. that's no good. by threading the adjustment ring until it's flush against the bottom bracket, you remove all play and preload the bearings. it's only supposed to be hand tight.

  4. #4
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    oh, and there should be a gap between the nut and the crank arm. it shouldn't be that big of a gap, but it's there. if you have any more than 2 or 3mm, then you probably didn't use enough spacers on the bottom bracket shells.

  5. #5
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    Great. Thanks, that makes things clearer.

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