Shimano BB-UN55 Cartridge Bottom Bracket
The UN55 bottom bracket is an improvement over the tried and true UN54. The sealed cartridge unit makes a great replacement part for hybrids, road bikes and older mountain bikes. The sealed cartridge bearings lock out contaminants like water and dirt, helping this bottom bracket last longer.
- Maintenance-free sealed cartridge bearings with high-efficiency rubber seals
- Square taper chromoly spindle