Why is the bb tube so much wider than the shell? It looks like the frame is built for something else in mind? Does the black “fill” part have any other function besides accommodating a smaller bb shell?
by Raspieman
Why is the bb tube so much wider than the shell? It looks like the frame is built for something else in mind? Does the black “fill” part have any other function besides accommodating a smaller bb shell?
by Raspieman
6 Comments
Excentric bottom bracket. It allows a bit of adjustment in order to tension your chain.
It is an eccentric bottom bracket shell. It has a normal threaded bottom bracket inside, but you can rotate the outer part to adjust your chain tension on a single speed or internal gear hub wheel.
It’s an eccentric bottom bracket, the black part rotates so that you can tension the chain. Lots of bikes made to be used without derailleurs (single speed or internally geared) have them
It’s an eccentric bottom bracket used for single speed bikes with vertical dropouts, or the front crank of a tandem. It is made so you can loosen the bolts on the bottom of the bottom bracket and correctly adjust chain tension.
Probably an eccentric T47
Eccentric bottom bracket. It’s used to turn pedalling motion into creaks, clicks and frustration