How do you make a bicycle that never needs lube, never leaves grease on your pants, and always delivers smooth pedaling? Simple: Ditch the chain.rnFor its new Soho commuter bike, Trek replaced greasy metal links with a dry belt. Unlike other attempts at such bikes, the Soho is silky smooth to pedal. And it's the first to offer multiple speeds, using an eight-gear transmission inside the rear-wheel hubrnTrek recruited Gates Technology, maker of belt drives for Harley-Davidson motorcycles, to fashion a belt from carbon fiber and rubber that's squeaky-clean and doesn't stretch out. The biggest challenge-a two-year endeavor-was designing the perfect fit between the teeth on the inside of the belt and the aluminum cogs on therncrank and rear wheel. Make the teeth too long, and the belt would snag on the cog, slowing the bike down. Too short, and the belt would slip.
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