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Now that Shimano has released their own 12-speed MTB drivetrains (SLX and XT), I have the following question:

What parts of these drivetrains are compatible between Shimano and SRAM?

I would guess that chain, chainring and/or cassette (assuming wheels with the respective freehubs) would work with the rest of the drivetrain being made by the other brand while combining shifter and rear mech from different brands wouldn't work.

Is this correct?

  • Why would you want to mix. The systems are as far as I've read in different cycling magazines quite different. Even the chains and hubs are proprietary. – Carel Nov 17 '19 at 14:30
  • @Carel This question is just out of curiosity - however, I can imagine several concrete examples: The local bike shop might only have SRAM chains in stock while you have a Shimano drivetrain with a broken chain. Or you might want to swap wheelsets (incl. cassette) between different bikes. Or you decide that the 51t large cog on Shimano would actually make a difference for you and you don't want to swap the whole drivetrain. But, as I said, this question is mostly out of curiosity and for future reference since I think that I might not be the only person wondering... – anderas Nov 17 '19 at 21:02
  • Two important drivetrain characteristics that can determine compatibility (assuming cassette sprocket spacing is the same and chain geometry is also essentially the same) are shifter cable pull length, measured in millimeters, and derailleur actuation ratio, which is the the distance that the cage travels across the cassette sprockets divided by the cable pull to achieve it. If anyone has these numbers for 12-speed drivetrains, please add them to this wikibooks page: en.wikibooks.org/wiki/Bicycles/Maintenance_and_Repair/… – Cedric Eveleigh Dec 6 '19 at 13:51
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The key issues relating to compatibility is the width and spacing of the cassette sprockets (and chainrings), chain design and the design of the ramps and pins on the sprockets and rings that facilitate shifts. SRAM followed Shimano up to 11 speed but I believe they diverged at 12 speed.

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  • Argenti, I've read that SRAM's road 12s groups have bigger chain rollers than SRAM's own 12s MTB groups and Shimano's 12s MTB groups. I'm not sure SRAM and Shimano's 12s MTB groups are that far apart. I'm coming across some info that the cog-cog spacing may be very similar. I can't find any information that the chains differ in roller size. Do you have any other info? – Weiwen Ng Nov 19 '19 at 15:11

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