Would you seriously ride at night when it's so dark you have to use a light? Crazy, especially on a trail.
Oh, no, the headlight and such are for people to see me, not to go places where I can't see. The streets are lit up by the streetlamps, but that doesn't mean cars can see you, even with reflectors. Any kind of light helps, hence the blinky LED taillight. I suppose just one of the $10 lamps that eats double A's would work fine.
There are some local groups around here that do night trail riding that requires headlights to see. They're insane! Tree roots and other obstacles come up a little too quickly. Hit one and the person who was behind you suddenly has a new obstacle to worry about.
