Great pic man! So what is it that makes the rider very clear and the background blurry? I just got a digital camera (canon a70), and when I set it too ISO 200, shutter 1/80 and F50 for aperture, the pic looks pretty normal. Although it wasn't a moving target.
Is it more the shutter speed that does that effect, or the combination of aperture and shutter speed? Also, what part does ISO really play in it?
Anyways, awesome picture, definitely mag material!