The Shimano Deore XT RD-M8100-SGS is a 12 speed, long cage rear derailleur for 1x drivetrains with a 10-51T cassette. SHADOW RD+ and a cage bumper keep the drivetrain quiet.

What it's for

The rear derailleur for a Shimano 1x12 trail or enduro drivetrain.

How it works

SHIMANO SHADOW RD+: a stabilizer in the derailleur that holds chain tension. It reduces chain slap and dropped chains.

HYPERGLIDE+: tooth and chain shapes that let you keep pedaling while you shift, up or down the cassette.

13T pulleys improve efficiency and chain management.

Bump Stopper: a bumper on the pulley cage quiets chain noise, and tension is lower in the low gear.

Compatibility

• Cassette: Shimano 12 speed, 10-51T
• Chain: Shimano 12 speed HYPERGLIDE+
• Drivetrain: 1x
• How to check yours: Shimano 12 speed cassettes mount on a MICRO SPLINE freehub

Setup and installation

• Mounting bolt torque: 8 to 10 N·m
• Cable fixing bolt torque: 6 to 7 N·m
• Pulley bolt torque: 2.5 to 5 N·m
• B tension: line up the mark on the inside of the outer cage plate with the tip of the largest cog's highest tooth
• Chain length: per Shimano dealer manual DM-MARD001 for your frame type

Care and service

• Clean the derailleur and lubricate the moving parts and pulleys regularly

Specs

• Model: RD-M8100-SGS
• Speeds: 12
• Cage: long (SGS)
• Pulleys: 13T
• Series: Deore XT M8100

Pairs with

• Shimano Deore XT SL-M8100-R Shifter
• Shimano Deore XT CS-M8200-12 Cassette
• Shimano XT 12 Speed Chain 138 Links