How the Common Bike Is Poised for a High-Tech Reinvention
Three remarkable innovations are transforming the mechanics of the common bicycle. In fact, these new technologies may be the most significant developments in bike engineering since the original "safety" bicycle was invented at the end of the 19th century.
The traditional chain is one of the biggest weak spots on any bike. Increased force on a link chain produces strain on the links themselves. Over time, these links break-and once they break, you're usualy hosed. Failure is accelerated by the dirt and grime that chains accumulate because of their much-needed lubrication. And constant wear and tear from grabbing and releasing gears doesn't help a chain's lifespan, either.
Trek's drivetrain belt looks eerily similar to some we've seen in LEGO kits.
Enter the belt drive, which increases the efficiency of a bike's power train while greatly extending its life. At its core, this is a simple piece of technology not unlike a conveyer belt. A smooth, contiguous piece of rubber or plastic-based material moves around two rotating gears. In early prototypes of bicycle belt drives, nubs down the center of the belt grab onto gears, and an internal shifting hub changes the gears.
In addition to increased power efficiency, the belt drive doesn't need to be lubricated-there are no moving parts, and it's not likely to break for the same reason. How close are we to seeing belt drives? Close enough that Trek has already developed the prototype pictured on this page. The only real downside, aside from scarce availability, is that a purpose-built frame is required because you can't pop the belt drive off like you would on a normal bike.
Expect to see belt-driven bikes in mass production by the end of this year. It's an ideal fit for a low-gear city bike.
http://gizmodo.com/5745772/how-the-common-bike-is-poised-for-a-high+tech-reinvention