I have a ride that I do. It's 20 miles exactly. It's mostly flat except for 3 valleys. So, out and back, I get 6 hills. The worst hill is the one I turn around at after I climb it. It's .4 miles at 10%. The rest are all about 7%. Gives me about 1300 feet of climbing. That's enough to make me take a nap when I'm done.