The Shimano XTR BR-M900 Cantilever brake arms come in two different lengths. Which go in front, the long ones with the stamped "F" or the shorter ones?

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1 Answer 1


I presume you have two sets of two, and the picture shows one of each?

In that case the pair marked F would be front-brake. The longer brake arm gives you more mechanical advantage on the wheel where it helps the most.

If you have a single pair and they're mismatched in length, then something's wrong and two pairs have been mixed up.

  • 1
    Yes, I do have the other two corresponding arms as well.
    – user430
    Feb 11 at 8:14
  • @user430 to be honest I can't see a reason why you couldn't use the arms marked F on the rear, or vise versa. Having both arms the same length is definitely going to make the yoke cable's action more simple.
    – Criggie
    Feb 11 at 8:57

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