I do sometimes get "shrinking butt syndrome," though I can control it. I've seen it happen *lots* on group rides. We're doing a nice job holding our advertised pace, and everybody's promised to be good 'cause it's supposed to be a level 1 ride... but then one person puts on a burst of speed. That sight of their hindquarters getting further away activates something (both men & women) and suddenly there's a whole group taking off.

I confess, I *do* get the urge to catch people sometimes - just because it's fun. I'll say howdy, though, especially if they catch me on those cross streets!