thats not completely true. there is more than one angle to drive a double up at. you don't have to bring it back to the full 90 you can make the inside angle(the angle that is labeled on the drawing above) a smaller angle like a 75 or 70. this will change the shape of the wake and make it longer and easier to hit (it won't throw you as high but makes it easier to throw tricks off of) the 90 makes the wakes steeper and give you more pop but also take into consideration that these are harder to control because of the pop, hitting the double up at 90 as opposed to 75 changes the pop similar to whether you hit the 1st, 2nd, or 3rd wave the 3rd is the biggest, yet hardest to control. the second wave is most commonly hit. just try it out experiment with other angles or different waves, i like the 90 for its pop but the lesser angles for trying new tricks or when someone is learning to hit them. just don't go past the 90 or it gets pretty impossible to hit and messes it all up. also make sure you give it alittle throttle to make up for the speed loss around the turn and then pull it back alittle when you straighten out so the rider has a consistant pull and speed.
(Message edited by edward on July 29, 2004)