Cranks that whiz at high speed are not a desirable feature, they’re just an invitation for crud to get into the bearings

CW’s Undercover Mechanic turns his attention to the murky world of bottom bracket ‘optimisations’

Image shows bottom bracket
Bottom brackets of old had a lot going for them, argues our Undercover Mechanic
(Image credit: Future)

I was recently servicing an old vintage mountain bike from the 90s and was struck by how smooth the bottom bracket bearings were after almost 40 years. With modern bottom brackets, I would count myself very lucky to find bearings performing so well after even 40 months.

How have we got here? And why does it seem impossible for manufacturers to get bottom brackets right these days? I think to understand where it has gone wrong, we need to look at the evolution of the bottom bracket.

undercover mechanic
Undercover Mechanic

Cycling Weekly's Undercover Mechanic will be publishing his thoughts on the state of the industry once a month. He's been working with bikes for over two decades, offering servicing on models from some of cycling's best (and worst) marques. You'll find him at all major trade shows and events, just don't expect him to make himself known.

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