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The Shimano Zee M640 deraillauer.

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    The Shimano Zee M640 deraillauer.

    This an interesting part for a few reasons.
    The only actual SS short cage MTB derailleur I've seen ( other MTB "short cage" are actually GS mid cage derailleurs) It's a DH rated part (son of Saint).
    It's sold as 10s but rumor has it that 11s works just fine (moron this later).
    It has metal parts that other 11s don;t have. Cover for the clutch assy, and metal clutch actuation lever. Also stamped steel rear swing bracket with integrated cable arm.
    2 versions DH rated for 11-28 cassette, and FR version for 11-32t-36t cassettes Both have SS cages. The FR has been used up to 11-42t on hardtails. It seems Shimano leaves some room for chain growth on full suspension bikes that can be used on hardtails.
    Now for the theoretical part.
    Shimano 11s, and SRAM 1:1 deraillauers ended up with the same cable pull ratio. 1:1.1 (1:1.12 Shimano) So SRAM NX 11s Gripshifters are on the menu.
    This is also the same ratio as classic 8/9s SRAM 1:1 shifters X0,9.0,8.0,7.0 etc. Twist or Trigger. So 11s clutch type derailleur on 1x8/9 bikes. Actual Shimano stuff won't work for 8/9s.
    So this looks like a rugged ,compact, versatile derailleur for Ebike conversions.
    Last edited by Retrorockit; 04-26-2024, 10:05 AM.

    I found this about using these with 8-9 speed.
    "Works with Shimano 10 speed drive trains when used with Shimano shifters, but can also work with 9 speed drive trains by using 9 speed SRAM shifters."
    Last edited by Retrorockit; 05-25-2024, 07:08 AM.


    • Retrorockit
      Retrorockit commented
      Editing a comment
      Why short cage?
      "Short cage is all you need for a 1x drivetrain on an 11-36t (or even 11-40t) rear cluster. What are the benefits:

      slightly shorter chain;
      short cage less likely to get damaged."
      Last edited by Retrorockit; 05-25-2024, 07:08 AM.