Underbike

Lie on your back, on a long padded bench “seat”, head between the front tires, facing front. A shoulder rest holds you comfortably, and you buckle yourself in place with straps.
Refer to the napkin illustration [link], which includes a stickman representing the rider. It’s a 3-wheeler, with a large tire in back, and two smaller ones in front. The front tires are connected by a rod, similar to a soapbox derby racer. Steer with your hands – the handlebars are connected to that front rod. Brake levers (not shown) are on the handlebar grips. Pedals, which have straps to hold them to your feet, are above the rear tire, and a chain connects to a gear on the tire hub. It uses the new “automatic shifting system” found in some modern bikes to eliminate gear levers, while allowing easy pedaling uphill. The seat and handlebars are adjustable for rider size.
Note: In this version, you will definitely have to pedal "backwards" to move forward. A simple addition of one gear will allow ordinary pedalage.