Over the past several years, the programs have sprung up and taken off in dozens of cities, on a scale no one had thought possible and in places where bicycling had never been popular.
The new systems are successful in part because they blanket cities with huge numbers of available bikes, but the real linchpin is technology. Aided by electronic smart cards and computerized bike stands, riders can pick up and drop off bicycles in seconds at hundreds of locations, their payments deducted from bank accounts.
Programs in Germany and Austria tend to work on a different system: Members receive cellphone text messages providing codes to unlock the bikes.
The actual impact of bike-sharing on traffic or emissions is difficult to quantify because converts include people like Monllor, who would have driven, as well as those who would have taken public transportation.