Originally Posted by
globecanvas
If the lights are for seeing, rather than just being seen, Exposure Lights gives you by far the most light for the weight (though they are expensive):
http://www.exposurelights.com/
Actually, that isn't quite true. If you compare, for example, the Lupine Betty @1850 lumens to the Exposure Six Pack @1800 lumens, respective weights are 485 and 490 grams. And the Six Pack is handlebar mount only, where the Betty can go on bars or helmet. The Betty is slightly more expensive, though, and has a better real-world run time.