Tynan said:
so 85 people that can average 24mph over 10 miles then?
Another factor of 10 maybe

so we need 850 of us and treat it like a rolling relay, picking up and dropping off riders as you go along. Aim for a constant peleton of 10 riders and you all do 10 miles each with your front mile being your last. As one peels off another joins the back, like a team time trial.
Logistical nightmare but not impossible, though no doubt there'd be something in the rules that negated this approach.