I'm using the cree style lights on both road and mountain bikes - the elastic rubber bands are ok, but they seem to work their way down and point at the floor.
I'm sure I once saw a custom mount that screwed to the bottom and then qr bolted onto the bars, but I can't find it now!
Was I making it up? Have you seen it or have you had a better idea?
I don't want to cable tie it as I only put it on for night rides
Hope do one.
Or you could bodge one from a quick release water bottle mount like what I dids.
[img] 
[/img]
I find that mounting the lights upside down, still using the rubber bands works fine...but neat idea there zippy kona.
Halfords do a mount for a fiver. It's a qr style like the hope. Takes 2 minutes to mod it.
It's what I use
Presumably it depends on what the bottom of the light looks like. Mine was attached to the concave bit at the bottom by a single screw. I was able to remove this and adapt an old mount for a Vistalite I had to the same screw. Result = secure QR mount. The Chinese Cree lights all vary a bit though. More to the point the battery will probably fail / set on fire soon anyway.....
Hope one my wife's MapDec light.