The cats over at Popular Science came across this fancy bike called the Novara Gotham. This is a bike that claims to have infinite, yes infinite gears. How does this bad boy work?
In a nut shell it uses a continuously variable planetary drive train. This fancy little gadget is adjusted by a shifter on the handle bar. As you change the shifter it changes the position of these balls inside the fancy gadget, there by changing the gear ratio. It is all about how much you rotate the gear shifter, not which gear disc you are on.
How about this, they provided this lovely video detailing exactly how it works. Check it out for the Full download.
more: Popular Science