Shimano BB-UN300 Bottom Bracket - English, 68 x 122.5mm Spindle, Square Taper JIS, 50mm Chainline

The Shimano BB-UN300 bottom bracket features a 68mm English-threaded shell paired with an extended 122.5mm spindle to establish an optimal 50mm chainline. Engineered for square taper JIS cranksets, this cartridge unit utilizes a weight-saving hollow spindle design to deliver smooth, dependable rotation on everyday rides.

Finished in black, it threads cleanly into frames requiring a standard 1.37-inch inner diameter bottom bracket shell.

• Shell width: 68mm
• Frame interface: English-threaded (1.37-inch I.D.)
• Spindle profile: Square taper JIS (hollow)
• Spindle length: 122.5mm
• Chainline: 50mm
• Crankarm fixing bolts are sold separately