Put all your limbs to use.
Ever since someone put a chain on the dandyhorse, cyclists have been using only a fraction of their energy potential.
A new bicycle design eliminates that inefficiency: it allows riders to pedal with their hands and their feet, putting forward-leaning weight to good use.
It's called the 4 Strike Bike, and though it is not the first bicycle with "two-wheel drive", its integration of upper and lower body strength is meant to be more highly coordinated than a simple tandem bike strategy. Invented by a Dutchman (no surprise there) named Lex van Stekelenburg, and rendered here by TSG Essempio, the 4 Strike Bike uses two chains to synchronize the body's movements. Left foot and right hand pump together, followed by right foot and left hand. Per Stekelenburg, the whole thing will feel quite natural:
If the whole body is brought to bear in the cycling process and is used to provide the energy for motion, as with four-legged animals, then the load on the body is more naturally distributed.
Or if comparisons to four-legged animals aren't captivating your imagination, think of it as cycling imitating swimming -- putting the whole body into one motion. Van Stekelenburg, a retired surgeon, says that while traditional cycling uses about 50 muscles, the 4 Strike would use 78.
The obvious issue here is that the 4 Strike Bike might compromise your ability to steer, though the site says it has a "steering stabilizing mechanism." It's also possible to deactivate hand-steering by disengaging the chain and locking the handlebars in an upright position for a more traditional ride.
All images courtesy of 4StrikeBike.