Loz Blain – 
The Carpii 4ciclet’s fairly narrow frontal profile makes it reasonably nimble in traffic (Credit: Carpii)Here’s an odd little commuting curiosity from Romania called the Carpii 4ciclet. It’s a four-wheeled stepper cycle targeted at older riders that transfers most of the pedaling work from the quads over to the calves, back, abs and backside. It’s creator claims it’s a particularly energy efficient design, but it sure looks odd to ride.
One stands upon the 4ciclet’s angled footboards, either resting on the seat or standing up for a bit of extra pedal power, and pushes down with alternate heels to get the thing going. Each pedal is connected to a lever that pushes down and directly applies torque to one of the 12-inch wheels, like so: https://youtu.be/DxWNG40tv4o It’s a single speed device, adding to mechanical simplicity but restricting the speed range. The designer says he’s tested it from walking pace up to 32 km/h (20 mph) thus far, and that you need to stand up and give it a bit of gumboot to get up a hill.
(For more information visit: https://newatlas.com/carpii-4-wheel-bike/54904/)