We will study what the wheelbase does in skateboarding.
In summary, it affects a skateboard's steering angle and how it pops against the ground. Let's objectively analyze what it does using 3D models and a physics engine.
Definition
What is the wheelbase to start off?
The wheelbase stands for the distance between the front and rear wheels, which also affects the steering angle.
The steering angle in skateboarding is an angle between the back and front trucks.
The arrow in GREEN: The direction of the rear truck.
The arrow in BLUE: The direction of the front truck.
The angle in YELLOW: The steering angle.
Impact of the wheelbase in turning
How does a skateboard turn?
A skateboard turns by pressing down both trucks by bending your ankles or leaning your body axis in the direction you want to go.
What happens when you press down the trucks?
As you press down trucks, they face different directions; the front truck faces the direction of the blue arrow, and the rear truck faces the direction of the green arrow.
The sum of these vectors determines the direction of a skateboard, which is parallel (or close to parallel) to the board.
The board has the energy to move forward. So why turn?
While it has an energy to move forward, the board turns due to the difference in the travel distance between the inner and outer wheels.
You can see the inner wheels' travel distance in yellow is shorter than that of the outer wheels' in red. When the board tries to move forward, the outer wheels travel longer than the inner wheels, causing the board to turn.
Why does a longboard turn slower?
The difference in the inner and outer wheel's travel distance causes a small impact on a longboard. Assuming the wheelbase is 100cm and pressing down trucks shortens the travel distance of the inner wheels by 10cm than the outer wheels.
In this case, the yellow line shortens by only 10% compared to the red line. Such a small difference causes minimum impact on the turning radius.
Impact of the wheelbase on a short board
On the contrary, when a board's wheelbase is 20cm, it greatly impacts its turning radius. When pressing down trucks shortens the travel distance between the outer and inner wheels by 10cm, the yellow line's length becomes 50% of that of the red line's. This allows the board to turn more quickly.
Impact on pop
Definition, hypothesis, and condition of experiment
We will run experiments by changing the wheelbase without changing the board's length. Using a physics simulator, we will see if a board with a shorter wheelbase pops lighter.
We will free fall a ball that weighs 1kg on the tail from 1 meter high, and it stops moving right after hitting the first impact.
Result of experiment
While the tail with the shortest wheelbase hits the ground, the one with the longest stays in the air. This proves the common saying "the shorter the wheelbase, the lighter it pops" is correct.
Shorter wheelbase = Smaller angle of pop
Let's repeat the same experiment with heavier(5kg) balls. Under this condition, while all boards' tails hit the ground, a deck with the shortest wheelbase(lime green) stays low, and the one with the widest wheelbase(blue) lifts the highest.
This indicates a board with a shorter tail pops higher if you can exert enough force on the tail.
In this experiment, "the wheelbase" and "the distance from the tip of the tail and the rear truck" are inversely proportional; the wider the wheelbase is, the shorter the distance between the rear truck and the tip of the tail becomes, and vice versa.
Next time, we will conduct experiments without changing the length of the tail.
What board should you buy?
Ultimately, it depends on your style and preference, but remember that some tricks can be easier with a lower pop.
For example, as I mentioned in the content about the kickflip's pop, flicking your board can get harder when its angle becomes too big depending on the timing.
