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:
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. Well, maybe a lot of gumboot if this video is any indication:
Brakes are twin discs operated through the steering handlebar, which also offers a fairly tight-turning degree of steering lock.
Instead of hitting the quads, Carpii says, the 4ciclet gives you a workout in the calves, buttocks and dorsal muscles. It's targeted at "riders of a certain age," but there's a big-wheel version coming for off-road sporty usage that will include "dual independent suspension at each wheel."
Apparent problems with the design may include the fact that it's a bit more bulky and awkward to store than a bicycle, the fact that its small wheels might not deal well with kerbs and potholes, the fact that it doesn't seem to let you get much torque onto the wheels, and … well, the way it makes you look when you're riding it, which could uncharitably be described as looking like you're riding an analog Segway with an itchy bum.
Still, an interesting idea.
Source: Carpii