You forgot about "it looks cool" as being the reason for hanging off
And centrifugal force along with gyroscopic effect being the reason bikes don't fall over.
and....counter steering is using gyroscopic precession to turn fast!!!!
http://www.gyroscopes.org/how.asp And
http://www.tonyfoale.com/Articles/Balance/BALANCE.htm [Edited on 8-3-2005 by Mr_S]