A straight slope or constant incline, like a ramp, won't do the trick. With a bulldozer, you can create a steady incline. Then you have to dig it out in the middle and place the dirt on the top so that the jump really comes when riders hit the top. The landing ramp needs to be more of a straight incline. The spacing between the jumps also needs to be just right and is related to the riders, speed.
Riders can miss jumps that are too close together.
On the other hand, if the jumps are too far apart, riders can't carry their speed from one jump to the next. As a kid, I was always on a bike. I had a Stingray. As I got a little older, it was just the easiest, cheapest, and most convenient way to travel. Today, a lot of people young and old are getting back into different types of riding.