Cycling in Eastern and Central PA requires climbing ability. Even in the valleys, one needs to be able to climb.
One of my routes takes me from Fleetwood to Oley, across the Reading Prong - so I need to climb the Prong twice. It's about 600-800 vertical feet, depending on the route.
Another route takes me through the center of East Penn valley. You'd think it would be flat, but it isn't, due to the stream beds that cut across. The hills don't rise as much, but there are more of them.