What is the difference between this Shimano BB-UN50 and the BB-UN55 ? The former is hard to find for sale, the latter seems to be found everywhere : r/bikewrench
Shimano BB-UN55 bottom bracket - Cartridge Bottom Brackets - Bottom Brackets - Parts - Shop | Nevis Cycles
Shimano BB Un55 2017 | Cartridge Bottom Brackets for sale in Pitman
Shimano BB-UN55 Bicycle Bike Square Bottom Bracket 107-127.5mm Sealed Cartridge Bearing - AliExpress Sports & Entertainment