Why Does XTR Demand the Shimano SM-BB93 Bottom Bracket?

The Shimano SM-BB93 is the XTR M9000/M9100-spec threaded bottom bracket, engineered to match the exacting standards of Shimano's flagship MTB drivetrain. Built on the Hollowtech II outboard bearing platform, the SM-BB93 positions sealed bearings outside the frame shell for maximum stiffness and pedaling efficiency, and uses the smooth rotation and improved sealing performance that Shimano specifies for XTR-level durability in demanding mountain bike conditions. At 73g, the SM-BB93 is significantly lighter than previous-generation XTR bottom brackets while maintaining the smooth operation and sealing quality required for sustained high-output trail and XC racing use.

English threaded BSA shell, compatible with both 68mm and 73mm shell widths. Designed for Shimano XTR M9000 and M9100 cranksets using the 24mm hollow crank axle standard, and mechanically compatible with other Shimano Hollowtech II MTB cranksets. Installation requires a Shimano TL-FC36 or equivalent Hollowtech II BB wrench. Shimano also offers the XTR press-fit bottom bracket (SM-BB94-41A) for press-fit frames. For riders building an XTR drivetrain on a threaded English frame who want the correct OEM bottom bracket at the flagship tier, the SM-BB93 is the only choice.