Shimano UN54 square taper bottom bracket review

Unbeatable lifespan

Our rating 
4.0 out of 5 star rating 4.0
GBP £25.00 RRP | USD $41.10
Shimano UN54 Square Taper Bottom Bracket

Our review

Should outlast all the competition but carries a weight penalty
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Square taper cranks and bottom brackets (BBs) ruled until about a decade ago. They might be officially obsolete but they still live longer than anything else.


There are some superbly engineered square taper cranks still available online in the form of Middleburn RS7s, Shimano XT and Race Face Turbines.

As long as you fit it correctly and tightly, the UN54 bottom bracket is squeak-free and stiffer than you’d expect given the external BB hype.


The last unit we replaced had run almost daily for close to six years, so you can’t beat square taper BBs for lifespan.

Product Specifications


Name UN54 Bottom Bracket
Brand Shimano

Weight (g) 296
Features 107 - 127mm axle
Bracket Type Cartridge
Fits Shell Width 68mm
Bottom bracket - crank arms connection Square taper