Bottom Brackets

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

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

• Lightweight seal structure removes grams • Durable anodized finish • Includes left and right hand cups, spacers, inner cover, and inner o-rings • Easy installation with TL-FC25 tool • Compatible with 24mm crank spindles • English, threaded: 68/73mm bottom bracket • Pressfit: BB86/92 bottom brackets

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.