There are very few roads in Illinois where you can not ride your bike, thus the lack of a definitive list. However, I was having trouble finding a list of links or other information about cycling off-road in the area, so I am putting one together. Enjoy, and if you have any other ideas or places that I missed, please email them to me so I can add them to the list. This list is not complete and may never really be complete. I'm updating this when I get a chance so check back.
Maps are a hot item and the most asked about in email.
This place has maps, books, etc. Lake County has very nice, detailed maps of their trails. The state of Wisconsin has a marvelous set of maps covering the entire state showing on road bike routes, recommended roads to ride, mt. I have a set and I hope they still publish these maps. Try the Wisconsin Dept. of Tourism.