Yeah, actually I would be surprised if it were 10 feet. We didnt measure but that was the biggest jump we could make in my friends yard and still have enough speed to do the flip. But anyway, 40 degree angle sounds pretty good. Its really not an exact science. I have done some on a 6 or 7 footer like the one in my avatar and I have done some on a 20 footer at a mountain. Once you learn it on something you won't get hurt on you will really understand how much speed and air you will need. The hardest part is making yourself do it in the first place...