three males and a female watch as a biker fixes a chain that has come off his gear on his bike.
The people watching are spectators.
Just because the people are watching, there is no way to infer that they are merely spectators.  They could be doing something.
exists e2 e1 s1 x1 x2 x3 x4 x5 x6 x7 x8.(Theme(e2,x5) & Actor(e2,x1) & v_fix(e2) & off(e1,x7) & on(x7,x8) & n_bike(x8) & of(x8,x3) & n_male(x3) & n_male(x3) & n_gear(x7) & of(x7,x3) & Actor(e1,x6) & v_come(e1) & (x5 = x6) & n_chain(x5) & subset_of(x3,x1) & as(x3,x4) & n_biker(x4) & n_watch(x3) & a_female(s1) & Theme(s1,x3) & subset_of(x2,x1) & n_male(x2) & card_eq_3(x2))
exists e1 p1 x1 x2.(n_people(x1) & exists x3.((x1 = x3) & n_spectator(x3)) & Actor(e1,x2) & v_watch(e1) & (x1 = x2))