Here at Perennial Cycle we love the German Busch & Müller dynamo and battery-operated lights! Germany has strict cycle lighting laws and B&M abide by them and we benefit from that. We have recently brought their battery powered Flat S Senso light into our shop and have found it to be a wonderful upgrade to a Brompton.
 
The Flat S Senso has both a light and a reflector, so it is legal to use this to replace a reflector on a bike. The Flat S Senso sports B&M’s LineTec technology which has a single LED as well as multiple mirrors that extend across the light in a  line, making you very visible on the road. In its Senso mode (S), the light turns on and off using light and  motion! This means that it will turn on whenever the bike is in motion and it is dark out  and it will remain on for a couple of minutes at a stop to keep you visible. If no further motion is detected the light will turn off on its own!


The light works on both rack (R) and non-rack models (L/E) of the Brompton. When installing it on a L/E (non-rack or non-fender) all you need to do is replace the reflector with the Flat S Senso. The reflector/light mounts on the the bike have a slotted hole that allows the light or reflector to slide up or down a bit. When tightening the Flat S light on, be sure and have the light as low in the slots as possible. This allows clearance with the ground when folding the bike.This light also fits very nicely on our Tubus and Racktime racks (also German engineering at is finest).