Originally Posted by
jeff-o
I should be able to see anything up ahead that would cause damage or whip the wheel out from under me, early enough that I can react.
Just seeing the obstacles/debris/potholes etc is not enough. To decide what to do about it, one needs a beam wide enough to know one's options. For my commuting speeds, a 2.6W / 6V dynamo lamp (powered by a battery pack) has been surprisingly good in that sense, because it gives a nice rectangular beam pattern.
--J