Details: Series: Deore XT M8100 Speeds: 12-speed Material: Aluminum P.C.D: Direct Bottom bracket not included Chainring not included Shimano Deore XT FC-M8100 Crank Arms Hub Spacing: Non-Boost (135/142mm) & Boost (141/148mm) Chainline: 52mm Q-factor: 172mm Average weight (32t): 620 grams Shimano Deore XT FC-M8120 Crank Arms Hub Spacing: Boost (141/148mm) Chainline: 55mm Q-factor: 178mm Average weight (32t): 628 grams Shimano Deore XT FC-M8130 Crank Arms Hub Spacing: Superboost (157mm) Chainline: 56.5mm Q-factor: 181mm Average weight ( 32t ): 636 grams Compatibility: The Shimano Deore XT Crank Arms are compatible with the following: Chain: Shimano HG 12-speed chains Chainring: Shimano direct mount chainrings: CRM75 , CRM85 , CRM95 Bottom Bracket: Shimano Hollowtech II Bottom Brackets Pedal: All 9/16" pedals