Gears & Crankset

[Gunk]

Let us know how you get on

 

[chriscross1966]

That's an early six-speed... based on the SRAM hub for which sprockets are very hard to find and therefore might be running the wrong sizes... plus the old single-piece crank. There are two ways to sort it out, neither are cheap but they do dodge any future issue with that rear hub. First thing, and for either way you go that crank and its associated bracket need replacing. The Brompton one is good but there are cheaper options and a compact 110bcd might make more sense. Secondly a new rear wheel. Either upgrade to a BWR hub to keep six gears and go with a front ring of around 44T, or put a Sturmey 8-speed hub in there (Kinetics and Brommie+ do them) and take advantage of the compact crank option with a 34T chainring. The 8-speed has the advantage of just one shifter (and cable come service time) plus a slightly wider ratio...

 

[Bee]

Maybe not even shortening the chain....I have both 58 and 38 tooth chainrings and hub sprockets ranging from 11 to 17 teeth. Much cheaper to by a larger sprocket than a new crankset with chain ring.

interesting 12boy! Does a 17T sprocket fit without needing to modify the frame? And as part of double-sprocket (6-speed) setup?

 

[12boy]

1 had no trouble with an 18 although this was on a 2 speed hub. Later Bikegang gifted me with an 11-14-17 setup. Both worked fine althoughbthectriple sprocket deal required a 10 speed chain.