I've got one I use for touring and weekend rides, but not commuting. Great bag, but I digress.

Short answer is, you'll need a workaround to use this with handlebars. I had a small (4 AAA) light on a Minoura extender (until the Minoura broke). The light couldn't light up the road, but was OK for a "be seen" light and also to hold down the map carrier when it started flapping at speed.

Now I've got a crown mounted dyno LED. That's one way to solve the problem! Another way is to get a "second handlebar", if you've got a threadless stem, and mount the bar to that. <http://www.sjscycles.co.uk/thorn-accessory-bar-t-shaped-105-mm-extension-0-deg-prod11040/> is the one I've got on a different bike, and it works like a charm. Note you'll want to get a second mount if you put it on a different bike -- the mount's aren't really movable.