Originally Posted by CyLowe97

If you were on a bike path it was most likely a rails-to-trails path, which means it was originally used for trains. Trains don't go up/down/up/down. They take the flattest and straightest path possible. That's why rails-to-trails may be great for a casual ride or walking the dog or jogging, but for a challenging bike ride, not so much.

There are hills in and around St. Charles, as the town straddles the Fox River, but this is not Kentucky. Kentucky has real hills. The Chicago area has the occassional river valley. The northern Chicagoland suburb of Wisconsin has hills if you go far enough west.