73 grams for a sealed, threaded bottom bracket with XTR-level bearings represents genuine weight savings without requiring a press-fit frame or ceramic upgrades. The SM-BB93 uses smaller diameter bearings than previous XTR bottom brackets, which dropped 21-25 grams compared to the M980 while actually improving seal performance. The redesigned sealing system cuts rotational friction by roughly 50 percent according to Shimano's testing, so your cranks spin more freely and the bearings stay protected from the mud, water, and grit that mountain biking throws at your drivetrain.

The external cups thread into standard BSA/English bottom bracket shells, and the kit includes three 2.5mm spacers to handle both 68mm and 73mm shell widths. If your frame has a threaded bottom bracket shell—and many riders specifically seek out frames that do—the BB93 installs without the creaking concerns and specialized tooling that press-fit systems can require. The included TL-FC24 adapter works with Shimano's standard bottom bracket tools for straightforward installation and removal. Thread the cups in with a bit of grease on the threads, torque to spec, and you are done. Serviceable and rebuildable if the bearings eventually wear, though the improved sealing means that timeline extends considerably compared to lesser bottom brackets.

Compatibility spans the full range of Shimano Hollowtech II mountain cranks with 24mm spindles. That means XTR cranksets from the M980 series through the current M9100 generation, plus XT, SLX, and Deore cranks that use the same spindle diameter. You can also run third-party cranks from brands like Race Face and FSA that use 24mm spindle standards. The black anodized finish on the cups and sleeves resists corrosion and looks appropriately understated against modern frame finishes. If you are running a mixed-level build with an XT or SLX crankset, the BB93 gives you XTR bearing performance where it counts most.... Read More