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.

Get the most out of SRAM's high-tech cranksets with the GXP Team Bottom Bracket. Built to last, this super-smooth bottom bracket lets your SRAM GXP crankset (sold separately) spin effortlessly without weighing you down.

- Simple and reliable square taper bottom bracket - Replaces both BB-UN26 and BB-UN55 - Sealed cartridge bearings - Cr-Mo axle - For bicycles equipped with a chain case, select BB-UN300-K - For E-type front derailleur compatibility, choose BB-UN300-E - Fixing bolts not included; Shimano FC-E6000 bolts suggested

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.

- Forged steel body - Alloy cups - Chromoly spindle - Sealed bearings - Interface: English - Spindle Type: Square Taper JIS - Weight: 290-300 grams

- One-piece bottom bracket cup set - Bearings included - Shell: 68mm - Spindle Type: OPC - Cup Material: Steel - Weight: 265 grams

- Simple and reliable square taper bottom bracket - Replaces both BB-UN26 and BB-UN55 - Sealed cartridge bearings - Cr-Mo axle - For bicycles equipped with a chain case, select BB-UN300-K - For E-type front derailleur compatibility, choose BB-UN300-E - Fixing bolts not included; Shimano FC-E6000 bolts suggested

- Thread: BC 1.37 x 24T - Caged bearing 1/4" x 9 - Fits most square taper cotterless BB axles - Spindle Type: SQR JIS - Cup Material: Steel

- One-piece bottom bracket cup set - Bearings included - Fits smaller american juvenile/youth sized BB - Shell: 65mm - Cup Material: Steel - Weight: 173 grams