Crowds of people are all riding bicycles.
people are riding
People are riding is a simplification of the original information.
exists e1 s1 x1 x2 x3.(a_all(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_bicycle(x3) & of(x1,x2) & n_people(x2) & n_crowd(x1))
exists e1 x1.(Actor(e1,x1) & v_ride(e1) & n_people(x1))