With its bike-rental system, Barcelona has joined a wave of cities looking to ease congestion and smog.

By ELISABETH ROSENTHAL

BARCELONA, Spain - In increasingly green-conscious Europe, there are said to be only two kinds of mayors: those who have a bicycle-sharing program and those who want one.
Over the last 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 sharing plans include not just Paris’s Velib’, with its 20,000 bicycles, but also wildly popular programs with thousands of bicycles in major cities like Barcelona and Lyon, France. There are also programs in Pamplona, Spain; Rennes, France; and Dusseldorf, Germany. Even Rome, whose narrow, cobbled streets and chaotic traffic would seem unsuited to pedaling, recently started a trial program, Roma’n’Bike, which it plans to expand soon.
For mayors looking to ease congestion and prove their environmental bona fides, bike-sharing has provided a simple solution: for the price of a bus, they invest in a fleet of bicycles, avoiding years of construction and approvals required for a subway. For riders, joining means low-cost transportation and a chance to contribute to the planet’s well-being.
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 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.
“As some cities have done it, others are realizing they can do it, too, said Paul DeMaio, founder of MetroBike, a bicycle transportation consulting company based in Washington, D.C., that tracks programs worldwide. “There is an incredible trajectory.”
The huge new European bicycle-sharing networks function less as recreation and more as low-cost alternate public transportation. Most programs (though not Paris’s) exclude tourists and day-trippers.
Here in Barcelona, streets during rush hour are lined with commuters and errandgoers on the bright red bicycles of Bicing, the city’s program, which began 18 months ago. Bicing offers 6,000 bicycles from 375 stands, which are scattered every few blocks; the bikes seem to be in constant motion. “I use it every day to commute; everyone uses it,” said Andre Borao, 44, an entrepreneur in a gray suit with an orange tie, as he prepared to ride home for lunch. “It’s convenient, and I like the perspective of moving through the streets.”
The expanding program in Barcelona is typical of so-called third-generation programs, which rely heavily on technology.
Here, a customer buys a yearly membership for about $30 and is issued a smart card that allows the rider to remove a bike from a mechanized dock. The first 30 minutes are free, with a charge of 30 cents per half-hour after that. A bike must be returned to any bike rack in the network within two hours or the card may be deactivated.
Most programs in Germany and Austria are different; members receive cellphone text messages providing codes to unlock the bikes.
In North America, issues like insurance liability, a stronger car culture, longer commutes and a preference for wearing helmets have slowed adoption of bicycle-sharing programs. None of the European programs require helmets. Still, Washington and Montreal are experimenting with small projects, and Chicago, Boston and New York are studying options. Sao Paulo, Brazil, also has plans to start a program.
Perhaps the best indication that bicyclesharing has arrived is this: Shanghai, which 10 years ago was trying to eliminate bicycles from some of its boulevards to make way for cars, opened a pilot bike-sharing stand in October.
The impact of bike-sharing on traffic or emissions is difficult to quantify .
Officials in Lyon, one of the first cities to institute a large technology-driven bike program, estimate that bike-sharing has eliminated tons of pollutants since its inception in 2005. But more than that, they say, it has changed the face of the city.
“The critical mass of bikes on the road has pacified traffic, said Gilles Vesco, vice mayor in charge of the program in Lyon. “Now, the street belongs to everybody and needs to be better shared. It has become a more convivial public space.
The Bicing program in Barcelona has had its glitches, reflecting, in part, its unexpected popularity.
Even with the growing pains, Jose Monllor, a graduate student, says he now rides to class. “It stays in the parking lot,” he said of his car. “It’s stupid to drive.