Northwestern and Evanston have a great bike path along the lake front and the city has bike lanes to improve safety for riders. It’s flat too so easy biking and there are bike share stations.
Purdue is also very bike friendly with bike lanes and there are nearby parks adjacent to campus to trail ride. Purdue has an interactive bike map that shows all the bike paths, bike shares, racks, etc… Added bonus at Purdue that if you forget to lock your bike, it will just get put up in a tree vs stolen. ; ).