What I was told ...
You want to keep your spine in a line that is parallel with a line through the centre of the bike. So, if you're hanging off the bike and your spine is 6 inches from the centre of the bike, your head should be 6 inches off the bike. A tip I was given was to try and get my chin down to my hand on the handle bar. I do have high, wide bars on the monster but you get the idea.
It's only a guide though, there's a plethora of styles in MotoGP and they seem nippy enough
