Shimano XTR M-981 Shadow Rear Derailleur $189.95
Built for precision.
Modern 150mm-travel bikes have different requirements in comparison to crosscountry race bikes, yet riders still prefer the weight, precision, and strength that's found in Shimano's XTR line. For them, there's the M-981 Trail Rear Derailleur; for the XC purest, however, Shimano's streamlined XTR M-981 Shadow Rear Derailleur fills the no-frills, ultra-light void.
Hovering around 50 grams lighter than the Trail rear derailleur, the M-981 Shadow forgoes the motion dampening switch. While this means it might permit more chain slap, the loss of mass on the parallel links and knuckle will offset that with quicker, effortless shifts -- what the racer needs.
For clearance, the M-981 uses Shimano's low-profile shadow geometry. This keeps it closer to the dropout and safer from impacts with roots and rocks. Both pulleys have sealed bearings, and the cage blends a carbon fiber outer- with an aluminum inner-plate in order to provide just--the-right combination of light weight, strength, and stiffness.
Please note that this long cage (SGS) model has a greater chain wrap capacity, so it's best paired with triple cranksets.
The Shimano XTR M-981 Shadow Rear Derailleur is designed to work in harmony with Shimano Dyna-Sys 10-speed Rapidfire shifters and 10-speed cassettes with a maximum 36t large cog.