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Can I put a stages XTR 9100 left side power meter on a XT 8100 crankset? Seems like it should work, but haven’t found a clear yes answer.

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    I’ll elaborate later, but to my knowledge you can’t. XT uses the old splined interface with pinch bolts, whereas XTR uses a single-bolt thing similar to SRAM DUB.
    – MaplePanda
    Jul 11 at 19:33

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MaplePanda is correct, M8100 is incompatible with M9100.

From the Stages website (emphasis added):

SHIMANO HOLLOWTECH II MOUNTAIN BIKE

For Shimano Hollowtech II mountain bike cranks, compatibility is a bit more difficult due to changes in the left crank between versions. If you are unsure, please submit a new ticket with Stages customer support detailing your current bike and crank model.

Current models (as of Mar 2023):

  • XTR M9100 12-speed: Works only with M9100/9120 cranksets, which do not use a pinch bolt attachment system on the left crank.
  • XT M8100 12-speed: Works only with M8100, M7100, and similar 12-speed Shimano mountain cranksets that feature two pinch bolts and are 20 mm thick at the BB end. Also works with older XTR pinch bolt style cranks.

Stages Power Meter Compatibility

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Since Ted covered the main points, I shall provide some supporting information and visual aids, as promised.

The XTR FC-M9100 and -9120 cranks feature a single-bolt attachment for the left crank arm.

enter image description here

This mates with short, relatively large splines on the crank spindle.

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For comparison, XT FC-M8100 and its relatives (-8120 and -8130) use the older style of left arm attachment, featuring two pinch bolts and a split.

enter image description here

This mates with a relatively long section of small splines.

enter image description here

This is the same joint design as XTR FC-M9000 and -9020.

enter image description here

Lastly, for comparison, let's examine XT FC-M8000 (also -8020). It has a wider left arm interface than both the 12 speed stuff AND the 11 speed XTR (for reference, see the gap between the pinch bolts). The difference is only a few millimeters, but that's enough to make the cranks non-interchangeable. The first image shows M8000, the second M8100.

enter image description here enter image description here

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  • Excellent detail. Is the reign of the two-bolt pinch on a Hollowtech II spindle coming to an end soon? And is there an advantage to the new XTR configuration? Questions for another post…
    – Ted Hohl
    Jul 12 at 14:09
  • @TedHohl I can make some educated guesses, but no definitive conclusion as to which configuration is better/worse. Feel free to write a new question!
    – MaplePanda
    Jul 12 at 18:52
  • So is an XTR M9000 left hand crank compatible with an XT M8100 bottom bracket spindle ( I can get an XTR power meter, but not XT)? Both seem to have the same double clamp bolt design.
    – Paul Darby
    Sep 27 at 20:03
  • @PaulDarby Tentatively, I would say yes, but without having tried that actual combination I can't guarantee it.
    – MaplePanda
    Sep 28 at 3:43

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