Have you wondered what would prompt a cyclist to do something like that one did?
Douche-baggery?
That's certainly a possibility, but I am going to guess, and this is based on experience, that it is due to too many unnecessarily close passes.
We’ve had discussions like this before and we’ve both laid out our positions so there’s no real need to hash it out again. But as for what you just said, you know I ride bikes and motorcycles. I’ve had plenty of close calls from close passes on both. Never once though did it occur to me to place a board with a flag on the end on either side to claim a lane.
Dude has balls though, I’ll say that much for him... 😁
