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 Movimento centrale, 122 mm : Amazon.it: Sport e tempo libero
SHIMANO Bottom Bracket BB-UN55
Qoo10] BB-UN55 73BSA 113mm
Amazon.co.jp: Shimano BB-UN55 Y1AS02000 Repair Parts, Left Adapter (B.C.1.37" x 24T), English Screw (Hanger Width 2.7 inches (68 mm), MM110, LL113, D-H, XL118, D-NL, D-EL) : Sports & Outdoors