Shimano Bottom Bracket BB-UN300 – reliable square taper bottom bracket for bicycles with BSA threading
The Shimano BB-UN300 is a high-quality bottom bracket with a square taper interface for bicycles with BSA threading. It is suitable for replacement or new builds of standard bicycles and provides durable and precise crankset support.
Square taper interface (4-notch) for compatibility with most standard cranks – easy replacement without special tools.
BSA threading (68 mm shell width) fits common bicycle frames – universal application.
Precision ball bearings ensure smooth operation and minimize friction losses.
With a 122.5 mm spindle length suitable for a wide range of chainlines.
The BB-UN300 from Shimano is the proven choice for anyone seeking a reliable bottom bracket. It impresses with easy installation and long durability – typical of Shimano quality.
Ideal for...
DIY enthusiasts, bicycle workshops, and anyone who wants to equip their bike with a reliable standard bottom bracket. Suitable for city bikes, trekking bikes, and basic mountain bikes with BSA bottom bracket shells.
How to install the bottom bracket
The bottom bracket is screwed into the bottom bracket shell using a suitable BSA tool. Observe the torque and correct alignment of the spindle. After installation, mount and tighten the crank. Detailed instructions are included with the product.
Shimano is a Japanese manufacturer of bicycle components and fishing tackle, founded in 1921. The brand stands for reliable, durable, and precise technical solutions. In the bicycle component sector, Shimano is among the world's leading providers.
The Shimano BB-UN300 is a bottom bracket with a square taper interface (4-notch) for bicycles. It screws into the BSA threading of the frame and accommodates the crankset.
It fits bicycles with a BSA bottom bracket shell of 68 mm width and square taper cranks. Typical for city bikes, trekking bikes, and basic mountain bikes.
The bottom bracket has a shell width of 68 mm and a spindle length of 122.5 mm.
The bottom bracket includes bearing and spindle. A BSA installation tool is not included.
Shimano offers a 24-month manufacturer warranty on the bottom bracket.
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