Then Dave poured concrete to secure the spring in the base.
Next they mounted an old non-functioning Bridgestone motorcycle to the spring.
Unfortunately the added weight and height made it too top heavy and wobbly, or in nautical terms, it was very tender. Dave hung on to the New Holland tractor for stability and wouldn't let go. It would definitely be too scary to spin around and bounce on this ride, especially so high up.
So it's back to the drawing board, but stay tuned, because you know eventually Dave will succeed!