How does throttle/rear brake change the bike's position in the air?

Question

I have a YZ 250F and I'm just starting to jump it. I was reading up on it and i hear a lot about using the throttle and rear brake to control the bike in the air. I was wondering how these things change the position of the bike in the air.

Answer 1

I'm not a motocross racer, but assume that it's simple physics: equal and opposite forces and momentum.  

There's always an equal and opposite reation.  Viewed from the side with motorcyclist jumping across your field of view from the left to the right, when they apply throttle the wheel accelerates clockwise pushing the motorcycle to accelerate counterclockwise, or nose up.  

The front and rear wheels are spinning clockwise, so when they apply the brakes, that momentum is transferred to the motorcycle, and it moves clockwise, or noses down.

Of course the motorcycle is heavier than the wheels, so in both cases the motorcycle is affected, but to a lesser extent than the wheel is (conservation of energy & momentum).

Answer 2

Hi, when your wheels are spinning in the air it makes your bike 6 times heavier than normal, so if you apply the rear brake the back of the bike will become lighter than the front and nose you in, if you apply throttle your back will become heavier and will lift the front of the bike for you. Hope this helps

Answer 3

It's pretty simple in application although I'm not going into all the physics involved. If you want to drop your rear wheel in the air you do what is called a "panic rev". The centrifugal force of the rear wheel spinning faster than the front pulls the rear wheel lower. If you want to drop your front end you do what is called a "brake tap". By stopping the rear wheel from rotating you create the same physics as before but in reverse.  

Answer 4

You really only need to use those two techniques if I really have to  because you can control the bike with your body without having to use those for every jump to position yourself but yes they work if you hit something on the upramp or it nosedives on you

Answer 5

The great Ricky Carmichael said in a magazine article to use your body positioning to control the bike most of the time. However, if you have been to the Red Bud MX National, you can tell that when they fly over the 140 ft. triple know as Larocco's Leap, they do use the rear brake to keep the front end from getting too high. Reason is that jump's face is so steep, when the bikes get in the air, the front end is very high. I would practice with body position and get good with that first.