kedo

I have been watching/studying dvd's of the GP and AMA seasons and have noticed that many of the pro's don't have their outside leg pinned into the fuel tank while they're "hanging-off". Why is this? How can they be "light on the bars" if they are not supporting themselves elsewhere on the motorcycle? Can their body positioning relative to the lean angle of the bike allow them to do this? I am very interested in your feedback here.