I use the Maxx-D Mk.4 by Exposure Lights, a British company and not too well known here in the States... and too bad, because their products are top notch and as good as these lights get. With 1285 lumens, I can max my speed going downhill on a dark country road and see a good 300-350ft. ahead.

It's built like a tank, weather-sealed, and on dark country roads I'm being yielded to from a 1/4 mile away because I'm being confused for an oncoming motor bike with bi-xenon headlight Unlike most other high-lumen lights out there, this one is an all-in-one, self contained unit. No cords, no battery pouch, etc. Quick release mechanism and you're good to go... 3 intensity levels, plus strobe mode.