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
Best Deal for SHIMANO BB-UN55 Square Taper Bottom Bracket (73x118-mm) | Algopix
Shimano UN55 Square Taper English Threaded Bottom Bracket - Trek Store of Bradenton, FL