Shimano dura ace r9100 bottom bracketthe shimano dura ace r9100 bottom bracket features smaller lightweight bearings and an advanced seal construction for smoother rotation and increased durability it is designed to work in combination with the dura ave r9100 crankset to offer optimum stiffness and a smoother pedal stroke features bb shell width 6870mm threaded bsa small bearings offer light weight advanced seal construction for smoother rotationa 2 year warranty is offered with all shimano