Today my neighbor and I went for a bike ride on the Old Plank Road Trail, in Illinois. It's an old railroad right-of-way, so for the most part, the ride is level and it's paved with asphalt. Easy riding. And easy on the equipment, too.
There IS, however, a subtle grade for at least the first 5 miles, which is SO subtle you never even realize you're going UP as you ride the trail. Until, that is, you turn around and go back.
It's as close as you can get to flying on a bike.