> IMHO, Terr's guess is exactly right. You get all the lift from pushing down the nose / dragging across the grip tape.

This is clearly not the case. The front foot guides the board, stops it rotating backwards, and is necessary to land the ollie, but it doesn't help get the board into the air.

The back foot pushes down (HARD) on the tail, the entire board rotates about the back axle until the tail hits the ground. At this point the front truck (which has significant weight (relative to the rest of the board)) is moving up and the rear truck is stationary, the momentum of the entire system is now up - the skater now (simply!) has to lift the rear foot at about the same speed as the tail lifts off the ground, and use the front foot to stop the board from over rotating back.

>Think about that for a moment. This is patently absurd. It's like trying to get several feet of air by crouching down and hitting the ground with a hammer. The collision is too elastic. //

It's not at all like hitting the ground with a hammer [but hammers will bounce on concrete FWIW and even flip end over]. It's more akin to a see-saw that isn't fixed down. If the force at the back of the board is sufficient to overcome the weight of the board pulling it down at the front then the board will rotate lifting the front. Once the back of the board hits the floor there is a new pivot point, the rear tip of the board (https://www.youtube.com/watch?feature=player_embedded&v=339k...). Now the board is rotating - in the clip - anticlockwise. But the front foot prevents this rotation and provides a further pivot.

You can do this experiment to demonstrate that a pivoted plank can jump. Take a ruler, place it on top of a rounded pen - this setup mimicking the rear wheel of a skateboard. Hit the ruler down at the short end and you'll see it flip up (it might take some practice!). Indeed the whole ruler, if it's short enough, might flip and continue rotating such that the long end goes up and over the short end - but this is because you don't have a front foot pushing that part down. Replacing the foot with your hand - as a barrier above the ruler preventing this continued rotation - leads to the ollie being imitated. The ruler jumps up with nothing other than a swift hit on the short end furthest from the pivot.

                                ( ) hand imitates
                                ( ) front foot
                                ( )
    ( )                         ( )   
    ( )
    ( ) hit
    ( ) down
    ---------------------------------
             O
             pivot, eg pen

Indeed, you don't even need the new pivot point of the back of the board either. If you smack the tail but don't drive it down the board will fly up into the air because the ground is resisting the pivot point of the wheels but the sky is not. The center of mass will start a linear trajectory once the pivot is defeated and I imagine that the angular velocity at the center of gravity will be mostly preserved once it takes off... My physics are rusty.

Yeah, you misinterpreted me. I didn't mean that just hitting something makes it fly up horizontally. I meant that if you simply stand on the tail of a board the nose points up and the whole board will fly upwards, like a seesaw. This is how you pick up your board if you're cool, stamp on the tail and it jumps into your hand. Small demo of that exact action: https://www.youtube.com/watch?v=JDU9wZUTLdU

The ollie is just that action with a foot sliding forwards to change the angle of the board.

Yea, I was being an idiot. I was interpreting some people's claims as the bouncing of the board being enough to propel the skater upwards. I guess nobody is saying that.

I really should know better since I can ollie. I think my mental model of the ollie put too much emphasis on the sliding.

Anyway, sorry.

I didn't say all the lift, I said "a bit more forward"...

The majority of the upwards movement seems to come from pushing down on the back, levering most of the board-mass upwards.