Originally Posted by
LeeG
the challenge is getting headlights with good beam shape and cut-off. It's easy to pack a lot of light in a reflector but a powerful cone shaped beam wastes half the light off the road and into others eyes.
If the light is entirely, stupidly installed...as in flat level to the road and aimed into infinity...maybe
some is wasted. But I see very few people that have lights so aimed. It only takes a few rides to notice that the light isn't hitting the ground and is being wasted. Most of us have our lights pointed at the ground at some point in front of us. Aiming the light is a much simpler process too.
Given that the light coming from a parabolic reflector leaves the light in a conic shape, there is only a finite amount of spread to the vast majority of the light being output by the lamp. There is some scatter but even shaped beams with cutoffs scatter some light.
The beauty of lights is that you can see...and get instant feedback...on where the light is going and can adjust accordingly.