I grew up in a small southern California town that had a sweet little community bicycle program. All the bikes were yellow, you could find them at various points downtown, and you could take them anywhere so long as you eventually returned them to the downtown area. The program was free and everyone loved it, but eventually it failed. Bikes were stolen, the system was poorly managed and so the program faded away.

Fast-forward to the recent past and every green blog worth its solar-powered servers was celebrating the bike-sharing program in Paris. I remember reading all the stories and thinking, "Good luck, Paris. We tried that in Ojai years ago and it didn't work."

Except this time it did. The Paris system is slick in every way: Cool bikes, reasonable prices, excellent placement of stations, and a process that works like a well-oiled machine. Officially launched in 2007, the Paris bike-sharing program today is nearing 50 million unique rides annually. It also spawned a modern wave of bike-sharing, this time done more professionally: Worldwide, there are now 300 other bike-sharing programs modeled after the Parisian system.

In the United States, modern bike-sharing launched with a pilot at the Democratic National Convention in Denver in 2008, which led to an official program there in 2010. The Minneapolis bike-sharing program launched soon after Denver's, running from mid-summer 2010 through late November. Since then at least a dozen other programs have launched and several more have been announced. Washington D.C.'s program has been successful to the point of creating problems (too many riders, not enough bikes). Portland announced its intention to move forward with a bike-sharing system last week. San Francisco and Chicago are expected to release requests for proposals from bike-sharing companies this year. New York City has narrowed its selection down to two providers and plans to eventually have 50,000 bikes--equal to the number of bikes in the Hangzhou, China bike-sharing program, currently the largest in the world.

These are not the first bike-sharing programs in the United States. There were dozens of community bike-share programs like the one in my small town dotting the country in the 1980s and 1990s. The difference this time around is not just that the bikes are cooler and the systems better planned to create links between transit nodes, but that a few key business ideas have added profit potential to bike-sharing's allure.

It started with advertising. By selling ad space on the bikes themselves and on bike-sharing stations, bike-sharing providers (sometimes municipal transit authorities, sometimes private companies, sometimes a joint venture between the two) discovered they were able to cover their costs. In some cases advertising combined with subscriptions and per-ride fees began to generate profits.

Raj Janagam, founder of Cycle Chalao! in India, had exactly this experience with his small bike-sharing pilot in Mumbai.

We did the pilot to test whether people getting out of railway stations would find these bikes to be an easy and faster transport option," Janagam explains. "Otherwise, they have to wait for a taxi or rickshaw for anywhere from ten minutes to half an hour. In the first month we had 33 subscribers for 30 bikes and we realized we had a profitable model.

Janagam went on to win a contract from Pune City to build and operate India's first city-wide bike-sharing system there. Last month he received even bigger and better news: India's Ministry of Urban Development has decided to do a 10-city bike-sharing pilot. The Ministry will provide 80 percent of the upfront funding for the systems to some of the country's most-populated municipalities, and wants the programs rolled out by the end of the year. Cycle Chalao! will compete to build and operate the systems. Janagam is convinced that by offering advertising across the system, in India's largest cities, the pilot will be as much a business success as it is a social one.

Of course in India, as in Europe, bike-sharing will likely be subsidized. In Pune City, for example, Janagam says city officials asked Cycle Chalao! to reduce their usual subscription fees in order to encourage ridership and make the system affordable to most people. The city will cover the difference, and Cycle Chalao! will turn a profit by selling advertising.