In Okayama, Japan, there is an amusement park with a roller coaster powered by the riders' feet. The ride is called The Skycycle, located at Washuzan Highland Park. The roller coaster is built on a hilly area, at four stories above the ground, taking advantage of the terrain. The carts that ride the roller coaster look a bit like side by side tandem bikes.
They have baskets in the front for storing belongings, and like a real bicycle have brakes. Washuzan Highland is a Brazilian themed park, with daily Samba shows and food. What would you think of riding a self propelled bike on a track four stories above the ground? You can check out more of the features of this theme park at its website.