 Hey guys, have you ever wondered why your bike leans forward or backwards when you brake tap or accelerate mid-air in a jump? In this episode I'll explain you all the physics behind this phenomenon and how to do it right every time, so stick around. The brake tap and the mid-air acceleration are a useful and common trick to level the bike mid-air, especially in motocross and supercross, where you have a lot of jumps to clear. The trick is simple, if you want the bike to lean forwards or stop leaning backwards, you tap on the rear brake. And if you want the bike to lean backwards or stop leaning forwards, you give it a small dose of gas. But how exactly does it work? This only happens thanks to rotational momentum and it's all happening on the back wheel. Let's take the example of the brake tap. On a regular jump, as soon as the bike leaves the jump, you stop accelerating and you let the back wheel spinning free. When you decide to brake tap, you pull the clutch to avoid stalling the engine and you hit the rear brake, locking the back wheel. In the precise moment you lock the back wheel, you make the wheel push the bike up, leaning it forward. To understand why, let's rewind a little bit. Let's brake the back wheel in four pieces. Each of those pieces have a center of mass to represent the mass of each piece in a single point. The blue and yellow pieces represent the most vertically distant pieces from the center of the wheel, as well as the swing arm. And the red and green represent the most horizontally distant pieces from the center of the wheel, but are aligned with the swing arm. You might be wondering why I'm explaining this, but bear with me. While the wheel is spinning, each piece has rotational momentum, which is responsible for keeping the wheel spinning at a near constant speed. As soon as the wheel gets locked, each piece goes from a certain rotational speed to completely stopped in a fraction of a second, and the energy of the rotational momentum gets converted in a tangent force. So we are left with four loads, equally in value, but different in direction. If we consider that these forces are applied to the nearest hinge, which is the swing arm's axle, we end up with four different moments of force or torque. The blue and yellow moments cancel each other out, since the length to the swing arm's axle is exactly the same, but in opposite directions. However, the red and green one do not cancel each other out, since the red is further away from the swing arm's axle than the green one. So the difference in moment between the red and green one causes the bike to rotate, and since it is mid-air, the bike is completely free and has nothing to prevent it from rotating, obviously. If you accelerate instead of braking, the opposite happens. Okay, this all sounds very simple, but what do you have to pay attention to while doing this? So nothing of this... happens to you. This phenomenon only happens when there is a big and abrupt change on the rotational speed of the wheel. So if you brake tap and the wheel is barely spinning, well, it won't lean much. And if you want to accelerate to lean the bike backwards, but you left the jump face accelerating, well, the small increase on the wheel's speed won't do much as well. If you thought there are no physics behind the smallest details while riding dirt bikes, well, you were wrong. There's a lot more to it than it sounds. To discover more about it, don't forget to like and subscribe to the channel. Cheers!