The other night, I was driving on this mildly busy road after darkness had fallen when I came upon three cyclists headed toward me with some really bright headlights...sufficient for the lighting conditions at that time. From the patterns of the lights, I could see that these guys were swerving all over the road, as non-organized groups often do.
Out of curiosity, as I passed, I checked my rear view mirror to see how well they were lit from behind. As I suspected, although these cyclists had invested good money in headlights that could blind oncoming drivers, they were using the usual little red blinkies on the back of their bikes. And these weren't even good ones, because had I not known to look for them, I probably would not have known they were there.
The overall effect was that these three riders, who were obnoxiously visible to oncoming cars were virtually INvisible to the vehicles approaching them from behind, on the same side of the road. It was clearly a dangerous situation as I noticed two cars slamming on their brakes at the last second.
I was compelled to turn around, catch up, and warn them that they could not be seen; however, by the time I reached a point where it was safe to make U-turn, they were gone.
If you're going to ride at night, think about lighting up on BOTH sides of the bike, OK? I hope these guys made it home to their families all right.