Standard Square Taper Bottom Bracket BB UN300 For JIS Cranks Pro Grade 68mm Shell 110mm Spindle BSA 68mm Hollow Spindle Cartridge Bearing Without Fixing Bolt Smooth Chainline Durable Replacement For Road And MTB Bikes

UN300 JIS Square-Taper BB with 110mm Hollow Spindle
✔️ 68 mm shell, 110 mm hollow spindle, single unit for JIS cranks

The UN300 bottom bracket is a sealed cartridge unit designed for JIS square-taper cranksets. It’s a common replacement for road and mountain bikes, delivering stable chainline and durable operation in a 68 mm shell.

✅ Fits JIS square-taper cranksets
✅ Hollow spindle
✅ BB Shell Width: 68 mm
✅ Spindle Length: 110 mm
✅ Cartridge bearing, UN300-style

💡 What is a bottom bracket cartridge used for in JIS square-taper crank setups?

A handy answer: It provides a sealed, cartridge-style bearing setup that fits JIS cranks, helping maintain chainline and smooth rotation.

- Sealed cartridge bearing for smooth rotation
- 68 mm shell width with 110 mm spindle
- Fits JIS square-taper cranksets on road and MTB
- Easy replacement on compatible bikes