Shimano BB-UN300 Bottom Bracket – British Thread 73x122.5mm LL123 | Durable Sealed Cartridge Square Taper Bottom Bracket
Upgrade your drivetrain performance with the Shimano BB-UN300 Bottom Bracket (73x122.5mm, British Thread LL123), a high-quality, long-lasting bottom bracket designed for traditional square taper chainsets. Engineered with precision bearings and a fully sealed cartridge design, the BB-UN300 delivers smooth, reliable performance in all riding conditions.
Whether you’re building a commuter, touring, or mountain bike, this Shimano bottom bracket ensures consistent pedalling efficiency and minimal maintenance, thanks to its robust sealed bearing assembly that keeps dirt, mud, and water out for maximum durability.
- High-Quality Shimano Construction: Built for traditional square taper chainsets, offering dependable performance and long-lasting reliability.
- Super-Accurate Bearings: Provides silky-smooth pedalling efficiency and reduced friction for improved power transfer.
- Sealed Cartridge Design: Maintenance-free unit prevents ingress of dirt, mud, and moisture for extended bearing life.
- Easy Installation: Simple, quick fitment with no need for bearing adjustment – ideal for home or workshop mechanics.
- Durable and Hard-Wearing: Designed to withstand the rigours of road, MTB, touring, and commuting use.
- Narrow Body Design: Allows extra clearance for frame cable routing beneath the bottom bracket shell.
- Use: Road, MTB, Touring, Hybrid, Commuter Bikes
The Shimano BB-UN300 is the ideal choice for cyclists seeking smooth performance, reliable durability, and easy installation. Its sealed cartridge bearing system ensures long-lasting, maintenance-free operation, while the precision-machined bearings provide smooth rotation for efficient pedalling.
Perfect for riders who demand quality and longevity, the BB-UN300 is compatible with a wide range of bikes using a square taper chainset. Whether you’re upgrading an older frame or building a custom setup, this bottom bracket offers the trusted Shimano reliability that cyclists around the world depend on.