The success story of cycling in Paris comes as heartening news at a time of concerns over global warming and increasing crude prices. US cities too could follow suit.
A year after the introduction of the sturdy gray bicycles known as Vélib's, they are being used all over Paris. The bikes are cheap to rent because they are subsidized by advertising.
About 20,600 Vélib' bicycles are in service in the City of Lights, with more than 1,450 self-service rental stations. The stations are only some 300 yards apart, and there are four times as many as there are subway stations, even in a city so well served by its metro system.
There are a Vélib' Web site, Vélib' fashions and a Vélib' blog (http://blog.velib.paris.fr/blog); one recent posting discussed the best way to ride with a skirt. A kind of Vélib' behavior has emerged, especially at the morning rush, with people swiftly checking for bikes in the best condition: tires inflated, chains still attached, baskets unstolen.
Natallya Ghyssaert, a 34-year-old doctor, has an annual subscription for 29 euros (about $46), which lets her use a bike whenever she wants for 30 minutes at a time without extra charges. She uses a Vélib' two or three times a day, saying, "I love it; you can see Paris, you can exercise and stay out in the light of day."
The Vélib' — a contraction of vélo for bike and liberté — can also be rented for a day or for a week, with a 150 euro (about $239) deposit taken from the user's credit card if the bike is not returned.
Rémy Pheulpin, executive vice president of JCDecaux, the advertising behemoth that built similar but much smaller programs in 10 other cities, like Lyon and Rouen, said the company had learned that there were several keys to success: allowing subscriptions, so people get the sense that the bikes are free once they have paid their up-front fee; making sure the bike stations are ubiquitous and keeping the system "user-friendly."
On the downside, there have been significant problems with traffic congestion and safety, vandalism and theft. At least 3,000 of the bikes have been stolen — nearly 15 percent of the total, and twice original estimates. Some have been seen in Romania or found in shipping containers on their way to Morocco.
Wearing helmets is not compulsory in France, and three people have died on their rented Vélib's, hit by buses or trucks.
Also drivers in already congested Paris, never particularly bike-friendly, are not excited.
"This is what the French call a 'false good idea,' " said Ronald Koven, who drives a car here. "The traffic jams are far worse, and because of them, the pollution is, too."
But the process presses on. While nothing like Amsterdam, Paris is also building more bike lanes, as well as reducing parking spaces by putting Vélib' stations in their place.
In the case of Lyon, rental bikes, with their distinctive silver frame, red rear-wheel guard, handlebar basket and bell, can also be among the cheapest ways to travel, because the first half-hour is free, and most trips are shorter than that.
"It's faster than the bus or metro, it's good exercise, and it's almost free," said Vianney Paquet, 19, who is studying law in Lyon. Paquet said that he uses the rental bikes four or five times a day and pays 10 euros (about $13) a year, half for an annual membership fee and half for rental credit that he never actually spends because his rides typically last just a few minutes.
"It has completely transformed the landscape of Lyon -- everywhere you see people on the bikes," said Jean-Louis Touraine, the city'deputy mayor of Lyon. It is France's third-largest city and had launched a similar system two years ago.
"The program was meant "not just to modify the equilibrium between the modes of transportation and reduce air pollution, but also to modify the image of the city and to have a city where humans occupy a larger space," he said.
The main complaint voiced by riders is that at certain times in certain places -- such as mornings at local universities -- all the racks can be occupied, making it impossible to return a bike. "I'm going to start using my own bike, because sometimes there are not enough spaces in the rack" at school, said art student Cecile Noiser, 19.
Company and city officials said that because the system sends in electronic data about which bikes are where, they are exploring ways to redistribute bikes using trucks to better match customers' needs. Touraine said the glitches are minor compared with the benefits.
Similar bike-sharing system could be on the anvil in such places as Brussels, Vienna, and the cities Cordoba and Girona in Spain. London, Dublin, Sydney, and Melbourne. Maybe the U.S. will catch on too.