I have mine mouted on my basket, which can be moved from one bike to the
other via a quick release. I used a tail reflector bracket and screwed it onto
the basket frame, then connected a chunk of pvc pipe this leaves room on
one side for my other AAA powered light if I want to run twin lights.
I had to wrap some rubber (rescue tape, love that stuff) around the PVC to
prevent the bands/mount from slipping down as I ride.
Recently however, the wires going into the battery pack pulled out. :-(
Since I ride an ebike and already had 24v or so going to the handlebars though
I decided to try and run the headlight from the 5v USB (formerly cigar lighter
adaptor) source there. It works ok, always indicates low batt (red) and is about
2/3 or so as bright as from the batt pack, but I never have to worry about if I
remembered to charge the lamp pack, or running out partway home.
