Shimano STANDARD BOTTOM BRACKET, BB-UN300, SPINDLE: SQUARE TYPE, SHELL: BSA 73MM, SPINDLE: 122.5MM (D-NL), W/FIXING BOLT

- 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