Which bikes use the Shimano BB-UN300 73 x 118mm Bottom Bracket?

The Shimano BB-UN300 73 x 118mm is the benchmark square taper bottom bracket for mountain and wide-shell bikes, a cartridge bearing design that delivers Shimano quality and smooth, consistent rotation in a sealed unit compatible with square taper JIS cranks. The 73mm English threaded shell and 118mm hollow spindle cover the common mountain bike and wider Q-factor configuration, so if your frame has a 73mm threaded BB shell and square taper JIS cranks, the UN300 in this spindle length is typically the correct replacement. A hollow chromoly spindle keeps weight down while handling real off-road power without complaint.

This bottom bracket ships without crankarm fixing bolts, which are sold separately, so add a pair if you do not already have them. Cartridge bearing construction means the bearing assembly is sealed and not user-serviceable, replaced as a complete unit when worn rather than repacked like cup-and-cone designs. Compatible with all square taper JIS cranks, including Shimano FC-series square taper cranksets and many third-party cranks using the JIS taper standard. Installation requires a Shimano TL-UN74-S or equivalent splined BB wrench. A straightforward, proven replacement for any 73mm square taper threaded bike needing fresh bearings.