I was out for a ride last night when i was passed (it was a recovery ride) by a chap with a little back up light tied to his collar and a blinky on his seat post.
At drafting distances it was just bright enough when we got in to Juniper Green the angle of the on coming car headlights due to the road being a bit narrower than Lanark Road and the fact i dropped back to 10m or so he had completely disappeared. Out of interest i moved to there road position where i'd be if i were in the car and he was still invisible.
I considered catching up and asking if he knew his blinky was so dim it could barely be seen and that his collar light didn't do what he was aiming for but decided against it. Should I have mentioned it?