Shimano Dura-Ace BB-R9100 Bottom Bracket

Shimano bottom bracket for the named series — the bearings the crank axle rotates on. A drivetrain service-item that affects rolling resistance and crank-arm feel more than most riders notice until it's worn out; replacement every 1-2 race seasons or every 2-3 training seasons is typical depending on weather exposure. Dura-Ace is Shimano's top-tier road groupset — the same parts the WorldTour peloton runs. Weight-optimised, finished to the tightest tolerances in the range. This is the Shimano Dura-Ace BB-R9100 Bottom Bracket.