OK, OK, I took care of the double post....now as to the photos....blurred images of bike riders was what I saw. And, as an art form, I can get into this. A rear curtain flash can be useful, or front, whichever gives the best result. Here is an example of a similar technique... http://www.flickr.com/photos/fantinesfotos/7569316256/sizes/o/in/set-72157630556228698/
where the goal is to see the people and have the car "in motion". This was actually my first attempt at this with the 16-35mm lens, and what I needed to do was set the focal point a bit differently so as to "rotate" the out of focus, blurred objects around the focal point. And, various shutter speeds can be used.
Here is another "slow pan"
I have not used the flash, but this might add some interesting effects especially in lower light levels. My personal preference in shooting sporting events is to record the action as I see it, if cars, bikes, whatever, to be able to see the faces clearly. However, I think the art effect in the "motion blur" photos is certainly a nice and valid technique.