Yowser. First off, after leading and organizing many rides, "everybody" is an intermediate rider. I rode just the white loop, well marked, fantastic day for a ride. I do know on the big advanced ride, two people had some injuries. That would slow the group down. And that there were 200 plus people all over the park. Group rides are not an exact science. I always take responsibility for where I am riding, ie. carry a map and such. Chilli prep started for the wicked ride, Ride, eat chilli, repeat.