Bottom Brackets

BB-UN26 cartridge bottom bracket. - Smooth rotation - Square taper spindle - Sealed cartridge bearing assembly

Shimano's BB-UN55 Square Spindle Bottom Brackets are the unofficial standard for English-threaded cartridge bottom brackets. Quality, value, and durability come together to keep you cranking for many, many miles. - Fits JIS Square-Taper Cranksets - Hollow spindle - Crankarm fixing bolts not included

Shimano's Ultegra bottom bracket uses Pro Tour-proven technology for lighter weight and super smooth spinning, while still maintaining the same level of durability and stiffness. It's available in English, Italian, or Press Fit models.

Compared to the power transfer of the conventional square taper spindle, the 8-splined OCTALINK interface that connects the bottom bracket and crankset increases the strength and rigidity for the entire assembly.

Shimano BB-ES300 Octalink V2 Bottom Brackets - Fits Shimano Octalink V2 Spline Cranksets - Crankarm fixing bolts not included

Shimano BB-ES51 Octalink V2 Bottom Brackets - Fits Shimano Octalink V2 Spline Cranksets - Crankarm fixing bolts not included

Shimano's Dura-Ace Track Bottom Bracket features smooth-spinning, low-drag bearings for maximum power on the track. The Octalink spindle provides a stiff, high-efficiency platform for your next effort at the Hour Record.