When I was a kid, the more gears your bike had, the cooler it was. Yet San Francisco is just crawling with single-speed bikes. On closer inspection, I found that many of these bikes don’t even have coaster brakes–they’ve got direct-drive chains. As long as the wheels are turning, the crank is turning, so you have to keep your legs moving, and you slow down by slowing down your legs. WTF??
It turns out that these fixed-gear bikes, or “fixies,” are something of a trend. Last year they were, anyhow. Here’s how to make a fixed-gear bike out of an old 1970s ten-speed, plus lots more info on why you might want one of these stripped-down, admittedly dangerous urban hipster rides.