Bottom bracket Shimano BB-UN300 square axle 127.5mm - EBBUN300KB27X

The Shimano BB-UN300 bottom bracket (ref. EBBUN300KB27X) is a reliable, cost-effective solution for bikes fitted with square-axle bottom brackets. Designed for frames with standard BSA threads (68 mm), it offers excellent robustness and durability, ideal for everyday use on the road, mountain bikes or urban bikes.

Featuring a 127.5 mm JIS square axle, this model is particularly well suited to triple cranksets or older systems Shimano. Its sealed cartridge design with steel bearings guarantees smooth rotation while limiting maintenance. Thanks to its solid steel and aluminium structure, it is highly resistant to mechanical stress and outdoor conditions.

Versatile and easy to install, the BB-UN300 is an excellent choice for replacing a worn gearbox while maintaining stable, efficient pedalling.

Key features :

• 127.5 mm JIS square axle ideal for triple cranksets
• Standard BSA thread (68 mm) compatible with many frames
• Sealed cartridge bearings for greater durability
• Robust steel/aluminium construction
• Low maintenance and easy installation
• Excellent value for money

TECHNICAL SPECIFICATIONS

Threaded bottom bracket
Frame mounting type BSA 1.37x24
Square axle length 127.5mm
Sold with crankarm bolts

FAQ - Bottom bracket Shimano BB-UN300

What is a square axle?
This is a classic standard where the cranks are fitted to an axle with a square cross-section (JIS), which is very common on entry-level and mid-range bikes.

Is this housing compatible with all bikes?
It is compatible with BSA threaded frames (68 mm) and cranksets with square axles only.

Why choose a 127.5 mm axle length?
This length is generally used for triple cranksets to obtain the correct chain line.

Is it suitable for everyday use?
Yes, it's designed for multi-purpose use: city, touring, mountain bike or road.

Does it require any maintenance?
No, thanks to its sealed bearings, it is virtually maintenance-free.