Shimano BB-UN300 Square Type Bottom Bracket – Durable Performance for MTB Riders

The Shimano BB-UN300 is a high-quality, performance-oriented cartridge bearing bottom bracket designed for mountain bikes with a 68mm BSA threaded shell. Featuring a JIS square taper spindle, it provides reliable power transfer and smooth pedaling for traditional chainsets.

Built with a sealed cartridge bearing assembly, the BB-UN300 keeps out dirt, mud, and water, ensuring long-lasting durability and maintenance-free performance. Its narrow body design also provides optimal clearance for under-frame cable routing, while the chainline stabilizer ensures precise and consistent drivetrain alignment.

Features:

• JIS square taper spindle for compatibility with traditional MTB chainsets.

• Durable sealed cartridge bearings for long life and minimal maintenance.

• Chainline stabilizer for improved drivetrain stability.

• Narrow body allows clearance for under-frame cable routing.

• Fast and easy installation without adjustment.

• Crankarm fixing bolts sold separately.

Specifications:

• Model: BB-UN300

• Shell Width: 68mm

• Shell Thread: BSA (British Standard)

• Spindle Type: Square taper (JIS)

• Sealed Cartridge Bearing: Yes

• Size: 68mm x 113mm

• Country of Origin: Shimano

The Shimano BB-UN300 combines durability, reliability, and easy installation, making it a perfect choice for MTB riders looking for smooth and consistent pedaling performance.