A bicycle is already pretty damn simple. Two wheels, a frame, a
seat, pedals and a chain. What happens if you remove the chains
though? That would give you the Bicymple—a bicycle that's even
more simple than you could ever imagine.  Why would you make a
bicycle without a chain? Well, aside from the answer of why not,
the folks behind Bicymple explain:  By removing the chain, the
number of moving parts and overall complexity is significantly
reduced. A direct-drive, freewheeling hub joins the crank arm
axis with the rear-wheel axis, shortening the wheelbase and
minimizing the design.  More than just a stylish concept bike,
the bicymple is comfortable, easy to ride, and brilliantly
simple to maintain. The lightweight design and short wheelbase
make for a nimble ride. The optional rear-steer mode is
reminiscent of custom "swing bikes" and allows tighter turns and
"crab-riding".  Because it looks fun as heck! [Bicymple via The
High Definite]