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
Cover Bottom Bracket SHIMANO Bb-Un 55 -4 7/16in BC1.37 X 24 Thread English New | eBay
Shimano Orta Göbek BB-UN55 68MM 113 Uzunluk
Shimano BB UN55 Bisiklet Bisiklet Kare Alt Braketi 107 127.5mm Mühürlü Kartuş Rulman|Alt Braketler| - AliExpress
SHIMANO - BB-UN 55 B22, BSA 4-Kant, 68/122,5 mm
Shimano MTB BSA UN-55 Bottom Bracket, Black | Bikeinn
Shimano BB-UN55 107mm 68mm BSA JIS keskiö - Filla Bicycles