Custom lots-of-titanium Brompton

^^ A variety of reasons really. A desire to something a bit different, doubts about the ergonomics of the Brompton's twin-shifter half-step gearing, a preference for the single thumb shifter on the 5 speed hub. And originally I was going for an 8 speed hub until I decided it was just too fat.

Another idea is using a Schlumpf 2 speed crankset.

It's also another way of adding 2 speed to your fixed wheel bicycle.