I wish i could find a diagram. When you turn the bike left, the wheels, tires (and everything under the pivot axis) move to the right, while your head, body, and everything else above the pivot axis move left. The bike does not pivot on the tires. If the center of gravity is too low, the bike will fall into a turn, and then NOT want to come back up. Higher center of gravity requires more work to lean the bike over, but it comes back up easier. It has to do with how far you are moving the center mass (the engine).