Originally Posted by Old Gammy Leg
Hmmm.... I can understand the arguments for carrying very heavy lights on a race bike, but I'm not quite convinced. I actually have a Cateye ABS system (10W + 20W) for offroad MTB. It weighs a ton, the 20W spot is IMO *too* bright for road use, and I often ride for longer than the battery life anyway. . . .
I don't think there is such a thing as "too bright for road use." Off road, it's you against the road. On road, it's you against speeding steel monsters. Off road, you have uneven trail conditions. On road, you have potholes, pavement cracks, glass, diagnal railroad tracks, sewer grates, etc., etc., etc. Bright lights are also more important if you ride fast at night with thin tires.
You may change your view of the importance of bright lights if, while riding with your LED, you don't see a pothole, crash, taco your wheel, destroy your derailleur and brake, rip your cycling clothes, nick your frame, and break your collar bone. On the way to the hospital, you can be happy that you saved a couple hunded bucks and a few grams.