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
BB-UN55 Bottom Bracket British Thread 73-113MM - Duff Cycles
Shimano Boîtier de Pédalier Carré BB-UN300 - bike-components
Shimano BB-UN55 68mm Square Taper Bottom Bracket - Rebec and Kroes Cycle & Sport