Turn the regulator ( C ) of movable wheel till the wheel touches the track ( A ) without any interval between ( A ) and ( D )  /  (A) and ( B ). 

Warning : Don't turn regulator ( C ) 1/2 circle or more which may cause the track break.

One completed  bending cycle: Turn the regulator ( C ) 1/4 circle each time then hold the handle bar ( E ) and turn the handle ( G ) clockwise to let track move from ( F1 ) to ( F2 ) then turn counter clockwise to let track move from ( F2 ) to ( F1 ). You can repeat  cycles to reach the desired curve.

Put track ( A ) into the bottom between movable wheel ( B ) and fixed wheel ( D ).( The part of aluminum side down, if for aluminum track )