I bought this kind of "upper beam headlights" for my bike: http://www.amazon.com/SecurityIng%C2%AE-3800Lm-Headlight-Headlamp-Bicycle/dp/B009QX8B2Q/
Maybe not the safest electronics* but dirt-cheap and bright as @$%&.
Disregarding some safety issues* I was annoyed by the cumbersome way of attaching and detaching it to my bike.
Well, ok, the included mounting material some kind of works, but... Meh.
So I was thinking about some quick-release solution for days and days until I had some bright moment when I saw my mini spring clamps, pretty much identically constructed to these: http://www.amazon.com/TEKTON-3901-Spring-Clamps-10-Piece/dp/B00BRL59UM/
or maybe more like these: http://www.amazon.com/Heavy-Duty-Muslin-Clamps-inch/dp/B004AZ38Z0/
Against all my expectations this worked so fine as it had been made for that purpose...
So see the next steps. *Not waterproof as described and the low battery warning does not work, instead it suddenly switches off, leaving you in the dark. The included charger / power supply gets pretty hot if the battery is fully drained. You´ve been warned!
But disregarding those 'minor' safety issues, it works fine ;)