three males and a female watch as a biker fixes a chain that has come off his gear on his bike.
The biker lost control of his bike.
The fact that the biker is fixing his bike does not infer that he lost control of his bike.  There is no implication that of how the bike has become damaged.
exists e1 e2 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 x1 x2 x3.(n_bike(x3) & of(x3,x1) & n_male(x1) & n_biker(x1) & Theme(e1,x2) & Actor(e1,x1) & v_lose(e1) & of(x2,x3) & n_control(x2))