for the past two years there's been a track-bike 'crit' on the cobbled streets of red hook in brooklyn, ny. google "red hook crit" for some more info. if you're doing this in an under-the-radar sort of way, you'll want to make sure that youv'e got your bases covered - 'marshalls' et cetera, to assure any POs that might raise eyebrows that everything is just fine and safe and you're not bothering anybody.