Bikers race through a forest.
Bikers compete in a race.
Bikers who race through a forest is a rephrasing of bikers who compete in a race.
exists x1 x2 x3.(a_topic(x1) & through(x1,x3) & n_forest(x3) & n_race(x1) & of(x1,x2) & n_biker(x2))
exists e1 x1 x2.(in(e1,x2) & n_race(x2) & Actor(e1,x1) & v_compete(e1) & n_biker(x1))