This is a picture I did not take

of a bike messenger on a bright Saturday morning riding down Market St. in San Francisco on a shiny, brakeless fixed-gear, while he gleefully rode along in the sunshine with his head up, down an unusually untrafficked block, when his front tire rolled right into the inch-wide gap into the steel air vent for BART (the subway) swallowing his entire front wheel up to the hub, sending him skittering to a stop, bewildered, still on his bicycle, gripping the handlebars and clenching his jaw, while his bicycle angled itself down as if he was riding down an impossibly steep hill on a perfectly flat street.