Lights on the helmet and bars (or lower in your case) is a great combo.

I use the Cygolite Expilion 250, which is bright and comes with a helmet mount. The supplied mount is nice because you can easily remove the light for daytime riding and is adjustable up and down depending on oncoming traffic. At 130g, it's almost unnoticeable, runs 3 hours on high, and has a nice beam pattern.

http://www.rei.com/product/807968

The reviews on the REI website are a little misleading with respect to the mount. It is tight at first, but with use, works much more easily. I think many gave up too quickly, and should have used it for longer.