In article ,
(MikeYankee) wrote:

Pilots must also look to the left and right as well as ahead. If you are
sitting up, you retain much of the horizon in your peripheral view as you turn
your head. Not so when you are prone.

In fact this is one of the most annoying things about riding "sport"
motorcycles where your torso is lying fairly flat on top of the fuel
tank. You end up with a lot of your weight on your wrists (unless
you're going *very* fast) which is tiring after only an hour or so, but
it is also quite hard to look to the side and behind when making lane
changes. Even looking "up" around a corner when leaned over 45 degrees
isn't all that easy on the neck.

This shot of me would have been damn near impossible on a sport bike:

http://koti.mbnet.fi/maajussi/nz_97/nz2pic29.jpg

-- Bruce