We now offer a Pinion gearbox option for custom Bromptons, alongside the rear hub gear options – it’s a bit more complicated than the other gearing options as it’s not a retrofit kit you can fit yourself, I have to modify the mainframe here, but it can be done to new or old Brompton frames.
Because of the extra space needed for the Pinion gearbox, a new longer rear triangle is also needed – this can be for the standard 16″ wheels, or you can go a bit larger and have 18″ Big Apple wheels. 20″ may be possible, but I haven’t done this yet 🙂
Because it’s one of my new rear triangles, it is ideally suited to disc brakes as well. I’m finalising exact pricing for this conversion, but as a guide a conversion with the P1.18 gearbox (18 gears, 636% range) with 18″ wheels and disc brakes, similar to my prototype, would be £2845.