How do motor cross riders know how fast to hit a ramp/jump to land safely on the downramp?


Like, how do they figure out how to not overshoot or case it? Was just watching a guy hit a heap of jumps in an arena and he got every single landing perfect.

In: 615

Most courses are designed so that you naturally get a good speed when you hit a ramp. So just going full throttle will usually give you pretty good landings. But you also see the landing ramp before you get to the jump, either on the previous jump or when going around the corner leading up to the jump. So you have an idea about how the landing looks as you approach the jump. And thirdly there is some room to manoeuvre in the air. By using the throttle and the brake in the air you can rotate the bike around. And you can also shift your body weight around to move the bike. You can do this to make adjustments allowing you to land shorter or longer once you see the landing.

The trajectory of freely falling body is well known. It follows a parabola of which parameters like maximum height, range, and angle of landing can be calculated. Air drag has to be taken into account I guess. I’m sure there’s lots of “practical wisdom” related to these and some rules of thumb for estimation.

Intuition. Thousands of jumps and you get a feeling for how much speed is needed when you see the face of the jump. It’s way easier to judge how much speed is needed if you first do a roll or just jump a bit at first. If he has hit those ramps and those distances during training he has jumped on them quite a lot and knows exactly what the correct speed feels like and what actions he has to take to adjust if that intuition tells him that hes not at the right speed.

You can do quite a bit in the take-off to adjust how far you will jump. You can seat-bounce to get more height and distance. For a seatbounce you sit down to compress your rear shock and get a bounce from it decompressing during the take-off.

You can similarly make sure your shock wont rebound before the take-off, often by simply letting go of the throttle, keeping throttle or compressing it while you leave the take-off to jump shorter.

You can also swallow the jump by moving your body similar to BMX-riders or do a “scrub” where you slide over the take-off, to get the kick of the shock in a different angle, and the momentum of the wheels and engine at a different angle, jump earlier and thus get less of a bounce and get in the air before you’ve reached the full length of the jump, making the jump smaller with less bounce from the shock.







Someone more into physics and math could check this out but there’s alot of forces and stored energy going on with suspension, rider position and the gyroscopic effect of the wheels and engine

The exact same way any other type of event requiring precision works. Experience. You don’t come hit the advanced ramps right off the streets, you practice for years to get to that point. They know what speed / gear / angle to hit the ramp because they have hit similar ramps hundreds or thousands of times.

So while the landing spot is just a function of speed and ramp angle, a skilled dirt bike rider will always be able to land a jump perfectly because they are actually able to control their orientation in the air. By using the rotational inertia of the wheels, and either applying the brake or throttle accordingly, they can ensure the bike stays in the proper orientation in the air. This is similar to the way a figure skater can change the speed that they spin by pulling their arms in or loving their arms out of during the spin.