How to… Execute an ollie
1. Basic forces
Due to factors like the skater’s position and their physical build, a rider possesses a certain amount of potential energy. This can be converted into kinetic energy to overcome gravity and friction, granting momentum. For tricks that involve spins and/or twists, part of this kinetic energy will transform into rotational energy. Velocity can be built by peddling against the skate surface, or by the rider lowering and then rapidly raising their centre of mass (ie crouching and then standing).
2. Generating air
The main technique used to get off the ground, without the feet leaving the board, is called an ‘ollie’. To do this the skater again crouches to reduce their centre of mass before quickly accelerating by standing rapidly. As they straighten, the rear foot presses hard on the back of the board, so it pivots counterclockwise about the rear axle and hits the ground. As dictated by Newton’s third law of motion, the reactive opposite force pushes both board and skater into the air, overcoming gravity.
3. The right balance
Now airborne, the skater needs to address an imbalance in board angle and their own centre of mass in order to stay in control. This involves the rider smoothly sliding their forward foot up the board, exploiting the friction between their sole and the board’s rough surface. This repositions the skater over the board without removing their feet from it, allowing their centre of mass to shift back towards the centre so they can ready themselves to draw the board parallel to the ground.
4. On a level
For the board to become parallel with the skate surface once more, the skater needs to push their front foot down on the board, raising the rear so that it’s on a level, while at the same time moving their rear leg towards the middle. These things need to be done in unison, and in a controlled manner, as if the boarder’s centre of mass shifts too far forward, they are likely to overcompensate, resulting in the front tip of the skateboard angling toward the ground and a potential wipeout.
5. Ready to land
The rider and board should now be parallel to the skate surface. At this point, velocity and momentum are allowing them to overcome gravity and air friction. However, they still have potential energy, which has been increased by their new, elevated position. As gravity overcomes the latter forces the skater lands safely by once more reducing their centre of mass, bending their legs and crouching. This enables them to absorb most of the upwards force generated on touchdown.
6. Coming to a stop
After the rider makes contact with the skate surface, friction instantly begins to reduce forward movement. As such, if no other force acts upon the skater, they will steadily be overcome by friction and gravity until they come to a complete halt. In contrast, forward momentum can be maintained – to some degree – by the rider raising their centre of mass after making contact with the ground/halfpipe, generating a small boost in speed, as we’ve previously seen in step
In summary…
Through this step-by-step, we’ve shown some of the core science behind skateboarding. For both jumping and landing, a low centre of mass (ie crouched position) is a must for better handling the forces at play. In addition, vertical acceleration of the body at the start of an inclined plane can increase speed, making it easier to generate big air on a halfpipe. Finally, the position of a boarder within any local environment hugely affects their potential energy, which determines the total velocity and momentum they can achieve.
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