At a time when motorists in their 000's are being persecuted for driving at perfectly safe speeds, sporting activities should not be allowed on public roads, unless the event is of sufficient importance to close the road. It wouldn't be allowed for a Boy Racers Club that fancied some fun.
Don't talk to me about careless drivers. I know all about it: I cycled hundreds (if not thousands over a period of years) of miles for fitness when that was an attainable end, until some daft old bint clipped my handle bar with her wing mirror and sent me flying. It was daylight, weather good, straight village road with excellent visibility, quite wide (generous for two cars, passable for three), no oncoming traffic, in fact no other traffic at all, 30mph limit, no excuse whatsoever. I was a bit battered but nothing serious but it was enough to put me off. She didn't even stop, probably didn't even realise she'd done it.
The roads are no place for sport.