A bicyclist is performing a trick on a tall tree.
A cyclists is changing a flat tire.
A cyclist may ride other cycles, like a unicycle, and not be a bicyclist.  Changing a flat tire is not typically considered performing a trick.
exists e1 s1 x1 x2 x3.(on(e1,x3) & n_tree(x3) & a_tall(s1) & Theme(s1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_trick(x2) & n_bicyclist(x1))
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_change(e1) & n_tire(x2) & a_flat(s1) & Theme(s1,x2) & n_cyclist(x1))