I’m not really a fan, if they are darting into traffic, going the wrong way on streets, riding at fast speeds on sidewalks, etc. I know we aren’t responsible for every cyclist out there, but when people encounter this type of behavior, it hardens attitudes. That increases political resistance to funding bike infrastructure and bikeshare. (I know bikeshare and alleycat racing are completely different worlds, but not in the minds of the hardcore bike haters.) It also makes me a little uneasy if a driver gets angered by this, then tries to take it out on someone else.