New Bicycle Bottom Bracket Bearing Cartridge Shimano

New Shimano Bottom Bracket Sealed Bearing Cartridge. Standard English Threading. ===aka=== British Standard Cycle Threading (BSC). ===aka=== Birmingham Small Arms (BSA). BC 1.37x24 - Brand New - Shimano Model: BB-UN54 - Shell width: 68mm - Thread pitch: 24 TPI - Outer cup diameter: 1.37" - Made in Singapore - Sealed Bearings - Square taper ends - 2x new crank bolts D-NL refers to a specific spindle length (approximately 122.5mm) and is designed to achieve a 47.5mm chain line. - This configuration is typically used for bicycles equipped with chain cases, where the right-hand cup sits slightly further out than on regular bottom bracket variants to accommodate the chain case. The BB-UN54 is generally interchangeable with the BB-UN300 because they are both standard square taper bottom brackets with the same threading + dimensions, but you must match the spindle width + frame shell width (68mm) for proper compatibility. The main difference is the BB-UN54 offers better quality, while the UN300 is a more budget friendly option with lower quality components.