"Bicycle designers from Hungary have revealed the Stringbike in Padova, Italy, a bike design that drops the common chain in favour of a wire and pulley system.
While it might seem like a complicated answer to a non-existent problem, the Hungarian creators assure that their symmetric system lends itself to an extra level of comfort and efficiency.
Typical bikes, of course, have a chain and gears on just one side of the bike. The Stringbike creators, at bike manufacturing company Schwinn Csepel Zrt, write that “asymmetry has been the source of lots of problems”. However, other than slipping chains and oily jeans, they’re mostly “unnoticeable” problems, until you’ve tried a symmetrical system first hand.
The new design’s mechanics are considerably more complicated than the traditional chain, and is possibly best left to the video (embedded below) to explain. In the most basic terms, the movement of the pedal forces a swinging arm to move about its shaft, pulling a taught cable around a pulley system. With each push, the task is swapped from the left side to the right.
The Stringbike offers up a few extra advantages over its chain-driven predecessor. The pedal system can be replaced with different discs for separate purposes, for example. Racing and touring could use different shaped and sized parts, to alter performance and function. Plus, the rear wheel can be removed in seconds, for portability.
You’ll also have no grease or oil to deal with, but it doesn’t look like you’ll be able to fix this quite as easily as replacing a knackered chain. The official website mentions that while you will be able to take it an appropriate service location, you can repair a Stringbike at home. Although, that would presumably be the least of your worries if a fast-moving, taught, metal wire lashed off its piston next to your leg. Ouch." Wired.com