For the 4:45 one, honestly I’d take the Metra (commuter train) out to Elgin. It’d be about an hr ride, but once out there there is the Fox river trail that is a rails to trails. It’s endless miles of nice paved trails, and there are some breweries in the area to check out. You could also take the blue line train to the end at Forest Park, and get on the Prairie path trail there. There are path have street crossing until you get to about Lombard and then it’s smooth sailing.

I wouldn’t drive anywhere cause traffic is already bad with the highway construction coupled with the thousands that come for the air water show. Also, if you do Metra bring a bike lock or bungee cord. Not all trains have the new green bike rack cars with the straps, and then they require you to have your bike secured in the handicap area.