A fibrosis of bicycle lanes is spreading through the cities of the world. The well-being of innocent motorists is threatened as traffic passageways are choked by the spread of dull whirs, sharp whistles and sanctimonious pedal-pushing. Bike lanes have appeared in all the predictable places—Amsterdam, Copenhagen, Berkeley and Palo Alto. But the incidence of bike lanes is also on the rise in unlikely locales such as slush-covered Boston, rain-drenched Vancouver, frozen Montreal and Bogotá, Colombia (where, perhaps, bicycles have been given the traffic lanes previously reserved for drug mules). Even Dublin, Ireland, has had portions of its streets set aside...