Yeah, the next two Sundays at the same place - Lakeview Industrial Park in Kenosha, Hwy 165 and 80th. Also a fun race at Blackhawk Farms raceway in S. Beloit on the 27th.
I believe there was a bit of heat coming off the road, plus that's a real tight crop. The riders were about 300 meters away at that point.
Re: that Sigma Lens. I like it's size and versatility but with the 40D I could never get a real sharp image. I could with the Canon 70 - 200mm f2.8 though. I'll keep working it with the 1D, see what it's capable of.
Thanks for the comments.