Shimano BB-MT801 BSA Bottom Bracket It's Threaded! The bottom bracket is what allows your crankset to smoothly rotate so you can pedal your way to your goals. Not all bottom brackets are made the same, with some being smoother and more durable than others. The Shimano BB-MT801 BSA Bottom Bracket is designed for Shimano 24mm MTB cranks. It uses high quality sealed bearings and is offered in threaded and pressfit. Features Designed for Shimano 24mm MTB cranks High-quality sealed bearings that roll smoothly and are durable Average weight: 84g | Shimano | Bb-Mt801 Bsa Bottom Bracket Bsa