Where's Wheels

Chicago Resources

Transit 

Chicago's CTA public transit system is fairly wheelchair accessible. When I was there I purchases a 7-day unlimited ride pass at O'Hare airport. The current price is $28 USD. You can get shorter and longer passes if you're not staying exactly a week. The pass start from the day you first use them which is really nice. More information about the pass can be found here 

https://www.transitchicago.com/fares/

Busses
At this time every bus in Chicago is equipped with a ramp and should be full accessible for anyone. 

L-Train
The majority of CTA's train stations have elevators or ramps to provide access for customers with disabilities. There is a list of the accessible L-Train stations here. 

https://www.transitchicago.com/accessibility/accessibleservices/

Other Services 

The city of Chicago has a webpage outlining some other accessible transit options within the city. However most of these service are only for those who live within the city.
https://www.chicago.gov/city/en/depts/mopd/supp_info/accessible_transportationinformationforpeoplewithdisabilities.html

Wheelchair accessible Taxi can be requested via open taxi.
https://opentaxis.com/

Bike Rental
Although I haven't tried them yet I found a place that will rent you a hand-cycle. This seems pretty awesome if you're with someone who is able bodied since you can both go for a ride. 
http://www.bikeandroll.com/Rentals.aspx?lid=1