The Shimano BB-UN300 is a simple and reliable square taper bottom bracket designed to replace both the BB-UN26 and BB-UN55 models. It features sealed cartridge bearings and a durable Cr-Mo axle for consistent performance.

• Versatile Configurations: Available in specific versions to suit various builds, including the BB-UN300-K for chain cases and the BB-UN300-E for E-type front derailleur compatibility.