If you ride you know those moments when you have fed yourself into the traffic, felt the hashed-up asphalt rattle in the handlebars, held a lungful of air in a cloud of exhaust. Up ahead there are two parallel buses. With cat's whiskers, you measure the clearance down a doubtful alley. You swing wide, outflank that flower truck. The cross-street yellow light is turning red. You burst off the green like a surfer on a wave of metal. You have a hundred empty yards of Broadway to yourself.