A concept!

Alpha Bike concept: free-wheeling fixie for flip-floppers

By Christopher Trout posted Apr 29th 2011 9:06AM

So Philliebot was a fail, but this chainless bicycle serves as proof that UPenn doesn't always come up short. The Alpha Bike, designed by a group of engineering students, contains an entirely internal drivetrain that allows riders to switch between fixed-gear and multi-gear setups. The simple switch is enabled by an electronically controlled clutch, part of the Switchable Integrated Free-Fixed Transmission (SWIFT), discreetly hidden in the bike's frame. Populating the front hub are a drum brake and a dynamo, which juices the bike's electronics -- the back hub contains a three-speed gear set, put in motion by a simple push-pull cable. When the front wheel starts rolling, an LED screen mounted in the carbon fiber handlebars is illuminated, displaying time, cadence, and speed, among other things -- this data and more is stored on an accessible SD card. As of now, the bike is still a prototype, but if you start saving now, you might actually have enough scratch to buy one when it comes to fruition.

*taken from http://www.engadget.com/2011/04/29/alpha-bike-concept-free-wheeling-fixie-for-flip-floppers/