It seems I'm late to the party, but just for the record: as mentioned, there's a model of Supernova E3 that's street legal in Germany. In addition, they sell a QR handlebar mount for the E3, and you can set up the wiring with a pair of plugs. You can then take the light with you when you leave the bike somewhere. In my case that makes sense, as the E3 is the single most expensive part of my winter bike. I wouldn't leave it attached to the bike.