The backside is to rotate 180 ° (skate and skateboarder) forward. Everything is in the shoulder movement, when you type the skateboard make a rotation of your chest of 90 degrees forward. The rest of your body and the board will follow. The frontside 180 is to make the backside but in the back. Look carefully the position of the feet and the direction in which the skater scratches on the videos in slow motion below.