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Thread: Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility content

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    Default Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility content

    Dumb question. I don't ask any other kind. Can you run a the current gen Ultegra left crank arm (R8000) on a current (M8000) crank spindle? They are the same 24mm spindle, right... What's going to mess this up and make it not work, the Q factor???

    Asking for a friend. it's me, who's thinking about a stages or 4iii which proliferate cheaply on forums and ebay for road but are waaaaay rarer and full price for MTB/XT left cranks.

    TIA, Smooches,
    John

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    Default Re: Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility cont

    You would end up with a left pedal closer to the frame than the rear one. It might feel weird or even worse make you sit with the hip not level because one leg would feel closer to the pedal than the other.
    --
    T h o m a s

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    Default Re: Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility cont

    Quote Originally Posted by sk_tle View Post
    You would end up with a left pedal closer to the frame than the rear one. It might feel weird or even worse make you sit with the hip not level because one leg would feel closer to the pedal than the other.
    Don't worry, he can use a road pedal on the right arm to compensate for the reduced Q-factor on the left. He will, however, need some cleat shims to account for the different shoe/pedal stack heights.

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    Default Re: Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility cont

    lol, probably not worth doing math. will just wait for the deal or next ebay coupon.

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    Default Re: Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility cont

    You should google and look at the parts.
    The older unit xt cranks took a much deeper spline than the Ultegra and da cranks.
    The crank is not the same grade of forging requiring a much deeper spline.
    The spline itself is the same... the depth is much different... ergo not interchangeable really.

    I would be surprised if this was not still true.

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    Default Re: Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility cont

    Are you looking to run the road crank on a mtb frame? It most likely will not work. I too thought about this shortcut, but the shape of the Shimano road and mountain non-drive arms are quite different. The road crank will fit perfectly onto the mtb bb spindle, but won't clear the mtb chainstays.

    My solution: both 4iii and Stages will mount their power meter onto your existing crank. (This is new for Stages.) I might go that route with my left XT crank.
    Geoff used to race around on a Brodie Sovereign
    Geoff Morgan

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    Default Re: Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility cont

    Back in the day of when HBO was our Netflix and square spindles roamed the planet, I used to swap road/mountain cranks around - mixing brands too!

    Come to think of it, all my mountain bikes still have that old square peg in a square hole set-up.

    Oh well, progress marches on...

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    Default Re: Long shot: Current Shimano MTB crank spindle -->Road Crank arm compatibility cont

    Ultra road compact , with 34 in the outer position will clear several frames OK, for a really nice, low Q factor setup.

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