The Frontside or Backside 180 The frontside or backside 180 is when the skater does an ollie, and then rotates their torso 180 degrees, which has the legs, and hopefully the board, rotate along with it. This may sound easy, but is hard because the feet can't loose contact to the board or it will not rotate the whole 180 degrees. The skater must rotate his upper half 180 degrees and the bottom half must rotate in the opposite direction. This is because angular momentum must be zero, since gravity the only force on the skater has no torque, the skate can't move the whole system. The skate conserves angular momentum. For the skater to get enough h1 he will extend his arms to increase his inertia to create a great enough angular momentum. When the skater lands on the ground he will rotate his torso, since he can exert a torque against the ground.