Originally Posted by
Milton Keynes
A while back someone posted a link to an article suggesting that reflectors on bikes are basically useless, as a car has to be directly behind the reflector in order to see the light reflected from it.
Incorrect.
A reflector is an array of small corner reflectors:
https://en.wikipedia.org/wiki/Corner_reflector
Corner reflectors send light back in the direction from which it came.
For this reason, it will always be brightest when the observer is co-located with the source of the light.
Reflective tape accomplishes the same thing using tiny glass beads.