Hey gotta intro this. It's preety hip on these thrilling bike riding game. I saw this on yahoo and it's one of the hottest flash game on the net today. Although it is simple but simplicity makes perfection. Just by drawling lines, you can ride all the way from top way down and on air as well. Check that out! Here's a video of this flash game.
www.linerider.org/play.php
This is one of the biker design.