Shimano BB-MT800 Pressfit Bottom Bracket

Shimano, XT BB-MT800-PA, Press-fit, BB Shell: 89.5/92mm, Steel, Black, IBBMT800PA

The Shimano XT M800 uses 24 mm axle and bearings, because the 24 mm diameter axle and bearings offers the best balance of rotating performance, stiffness, strength, sealing and weight.

XT has gone 11-speed, and the new Shimano XT Cranksets are spinning on XTR/Dura-ace inspired bottom brackets. They have a smaller bearing size to enhance rolling efficiency and for shaving some weight. They are also better sealed to reject whatever muck mother earth conjures up and tries throw at them.