I recently saw a great documentary on motorcycle racing in the US in the 1970s called On Any Sunday, directed by Bruce Brown (who also directed a surfing documentary called "The Endless Summer"). The film features various AMA racers of the day, such as Mert Lawwil, Gene Romero, Dave Aldana, Don Castro, etc. It also features Steve McQueen, who apart from being a great actor was also a great off-road motorcycle racer (he notably competed in the 1968 International Six Days Enduro in East Germany with the US team).
Even if you know nothing about motorcycling, try to see the film if you can; it's really worth it because it gives a great insight into what makes racers tick (although the bikes have changed dramatically since the early Seventies, the motivation is still the same). Here's a couple of clips from the film (thankyou, Youtube :wink: ):
http://www.youtube.com/watch?v=0vkopfn1gLU
http://www.youtube.com/watch?v=h-151wFnhtE
