Where are some good races in Chicago?

Those underground races sound like a great idea until something happens. Real sanctioned races offer much safer organized racing with proper support and insurance run by responsible people. You may think that the risk is worth it but you might be competing against some very dangerous riders. Most sanctioned racing requires an entry fee that covers you if you are injured as well as safer courses and better organization. If you want to give racing a try, start by joining a cycling club to learn to ride in a group.

Gee...here's a really wild idea. ASK at LOCAL bicycle shops - not on the world wide web.