The Shimano BB-UN300 Bottom Bracket British Thread is a good quality bottom bracket for traditional chainsets. Super-accurate bearings for smooth operation and improved durability.Shimano BB-UN300 Bottom Bracket British Thread FeaturesDurable, hard-wearing sealed cartridge bottom bracket with square tapered spindle fittingMaintenance-free sealed cartridge bearing assembly keeps out dirt, mud, and water for long bearing lifeFast and easy installation without adjustmentNarrow-body allows clearance for cable routing under the bottom bracket