Which Bikes Need the Shimano BB-UN300 68x110mm Bottom Bracket?

The Shimano BB-UN300 in the 68mm English x 110mm spindle configuration is a cartridge bearing square taper bottom bracket built for bikes where a shorter spindle produces the correct chainline -- primarily road and hybrid frames with double chainring setups where the shorter 110mm spindle positions the chainrings correctly relative to the dropout centerline. The integrated chain line stabilizer keeps lateral chain movement in check for more consistent shifting across the cassette or freewheel. Shimano quality seals and cartridge bearing construction deliver smooth, reliable rotation and long service life in a fully sealed, non-serviceable unit.

English threaded 68mm shell, JIS square taper interface, aluminum adapters, standard structure. The BB-UN300 is available in multiple spindle lengths -- 110mm, 113mm, and 122.5mm -- so confirm your required spindle length before ordering, as the correct length is determined by your crank model and desired chainline rather than bike type alone. Compatible with all square taper JIS cranks. Installation requires a Shimano TL-UN74-S or equivalent splined BB wrench. For the mechanic or rider who needs a trusted, no-fuss OEM-quality square taper replacement in the 110mm spindle length, the BB-UN300 is the go-to choice.