A quick web search found this bike club in Racine:

http://www.krbikeclub.com/

I don't know anything about them, but if you contact them and tell them where you are (cycling wise) and where you want to be (50 miles in Sept) they ought to be able to tell you if any of their regular rides would be good for you. Also, they might have some people training for this or other rides in the fall that would like to have you train with them.

Good luck.

Barbara