The Pendix electric motor system is the neatest retrofit system I’ve found for the Brompton. It is beautifully simple, the motor fits at the cranks and the battery fits onto the top tube – apart from a couple of sensors, that’s it!
Because it is a crank drive, it will work on any Brompton – no need to change brakes, wheels or gearing, no frame modifications are needed. It’ll also work with any of my custom Brompton options – it’s fine with the Rohloff and Alfine hubs and disc brakes.
Pendix Electric Kit for Brompton – £1745