Shimano RD-M8100-SGS (Deore XT): 12-speed rear derailleur

This is a 12-speed rear derailleur.

It is the Shimano RD-M8100-SGS (Deore XT).

It can handle a maximum sprocket size of 51 teeth.

Unlike the Shimano RD-M8000-GS, the H/L adjustment screws are arranged in a more typical layout.

The Shimano RD-M8000-GS weighs 283g.

Initially, I wanted to use this 12-speed derailleur with the other 11-speed Shimano components on my Cujo 1 (they are unofficially compatible). I wanted to change the Shimano RD-M8000-GS (11-speed Deore XT) derailleur because there was a lot of play in its connection to the hanger.  However, then I changed my mind and decided to switch to a 12-speed drivetrain completely.

See also related notes:

• Shimano M7100-1 (SLX): Crankset 175mm, 32T (2025-11-11)
• Shimano SL-M8100-R (Deore XT): 12-speed shifter (2025-11-03)
• SunRace CSM901 WA1 12-speed 11-51T cassette (2025-10-25)

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