Thanks guys. It took a lot longer to build than I had planned, but it has already been worth it. I get more of a work out on that track in 3 minutes of riding than I do in 30 minutes of mountain biking. It's insane. I'm glad it's not any longer, I can't even do two laps without running out of breath. I'm getting faster though, and I'm getting less tired each time I ride it. Best of all, my neighbors love it!
Now I've just got to figure out a way to keep my homeowner's insurance from taking the hit if anyone gets hurt, then we'll have a BBQ riding night.