SHIMANO BB-UN300 BOTTOM BRACKETSQUARE TAPERUnfortunately, all your moving components will eventually wear out and will need to be replaced to keep your bike working properly. When it comes to bottom brackets, you'll want to make sure you get the right bottom bracket to fit your bike and crankset. The Shimano BB-UN300 Bottom Bracket is an English-threaded, squared-taper JIS bottom bracket. It fits JIS square-taper cranksets and has a hollow spindle. FeaturesCompatible with JIS square-taper cranksetsCrankarm fixing bolt sold separatelyAvailable in several sizes so make sure you get the right size for your bike | Shimano | BB-UN300 Bottom Bracket 68mm x 122. 5mm (D-NL)