Ask The Editors: ATV Jump Physics
How are they doing this?
Good observations! So what we consider a jump is actually three different events in physics occurring one after another- The launch; where the combination of momentum and the angle of the ground give us a moment to literally defy gravity’s influence. The peak; that weightless instant where we stop climbing. The fall; when gravity resumes its hold and we start barreling back toward the ground.
It’s in that moment of weightlessness that the machine becomes easiest to manipulate. Riders accomplish this by moving in the saddle to manually change the angle of the quad but the most effective way to make big changes is to use the potential energy already there in the ATV.
The most common technique to bring the nose down in a hurry while airborne is to pull in the clutch and tap the rear brake. The above video is a textbook example of this technique. How does it work? When you leave the ground, the real wheels, chain and axle are still spinning. Now picture what happens when your brake pads grab the spinning disc and stop all of that momentum at once. That energy transfers into the brake and is sent through the chassis. It’s a jolt that rotates the whole quad in the opposite direction.
Conversely, if you leave the ground nose down, a quick stab of the throttle can have the opposite effect. Putting those rear wheels into motion can rotate the machine toward the back. This one seems to be a bit more instinctual as anyone who has ever sent their quad skyward has some concept of the “panic rev”.
There are a few things to remember, though. First is that it only works once per jump. Once you send that potential energy through the chassis, the resulting pitch change will be too advanced to be countered by doing the opposite. Second, pulling in the clutch is a must if you’re going to stomp that rear brake in the air. Stalling the engine up there can open a whole new can of worms. Like everything, this is all an exercise in timing and practice makes perfect.
