Back in the summer of 1965, a group of self-styled anarchists whitewashed 50 bicycles and stationed them in the centre of Amsterdam.
"We wanted to save the city," says Luud Schimmelpennink, 79, who invented the "White Bicycle Plan" as a member of the anti-establishment Provo movement. "The idea was that with free bikes and no locks, people would stop using the car."
The plan backfired - the bikes were confiscated by the police - but it offered a glimpse of the future. Now that playful act of defiance has gone mainstream.
With the bike-sharing boom still in its first decade, Asia is already outpacing European towns that started the phenomenon.
The Chinese cities of Hangzhou and Wuhan are the global leaders; India's megacities are struggling to take off; the United States is playing catch-up; Africa hasn't started.
From flat Astana, Kazakhstan, to Quito, Ecuador - with an altitude of 2,800 metres above sea level - bike-sharing programmes exist in more than 600 cities in 52 countries, says Russell Meddin, who maintains and updates The Bike-Sharing World Map, a website that surveys cycle plans around the globe.
Meddin, a bike enthusiast from Philadelphia, in the US, who has sampled programmes in China, Europe and North America, says 68 new ones have been introduced around the world this year - a rate of two a week.
By putting millions of cyclists on the road, bike-sharing is reshaping the design of cities by connecting mass transit, removing cars from city centres and creating new infrastructure. New York has built 480km of bike lanes, while Danish riders have their own road linking the capital, Copenhagen, to the suburbs.
"Bike-sharing will continue to evolve, as will the cities in which it exists," says Paul DeMaio, a consultant for the regional service in Washington, in the US, which has 2,500 bikes.
European cities with compact city centres, such as Milan and Barcelona, are more appealing to cyclists than the car-clogged streets of sprawling Karachi and Lagos. This may explain why the idea was introduced in the northern French town of Rennes, where 200,000 residents tried the first computerised system virtually for free in 1998; Paris adopted the idea in 2007.
The French capital, which boasts a network of 20,600 bikes every 300 metres, served as a model for places such as London and New York.
The idea then, as now, is simple: you get a key or a set of codes to unlock a bike from one of many stations across the city.
The first 30 minutes to an hour are typically free. After a journey, you park at the self-locking dock at or near the destination. There is usually a fee to take part - London charges £90 (HKS1,200) a year or £2 for 24 hours, although Buenos Aires, in Argentina, charges nothing.
As the craze swept east, China grew dominant, but India struggled. In seven years, China, the world's most populous nation, went from no public bikes to 650,000 - dwarfing France's fleet of 47,000.
This year China overtook Italy - whose own system in Rome is a case study in what not to do - as the nation with the most programmes, says the US-based Earth Policy Institute.
Once dubbed the "Kingdom of the Bicycles", China replaced bikes with cars in the 1980s as it focused on expanding its economy quickly. Now confronted by toxic smog and traffic jams, the Communist Party leadership has re-embraced the tradition, which only recently was shunned as backward.
A year after the Paris launch, China introduced the scheme in the port city of Hangzhou with 2,800 bikes - with fixed gears to limit the cost of theft and vandalism. There are now 65,000 bikes.
"I call it the big bang," says Meddin. "You have to go big right away and not waste your time trying to test it out first on a small scale. That just doesn't work."
It's a lesson India ignored. A quick glance at the bike-sharing map shows the nation of 1.2 billion people is a desert of micro-sized pilot schemes and feasibility studies that went nowhere.
Schimmelpennink, who still rides a bike every day in his home town of Amsterdam, flew last month to Bangalore, India's technology hub, which has only experimented with bike-sharing at a university campus. He was shocked to see a potpourri of death-defying rickshaws, honking mopeds and damaged cars snaking in and out of lanes. "It looks dangerous to be a cyclist," he says. "They've got a lot of work to do."
With the UN predicting the number of cities with more than 10 million people will grow 50 per cent - from 28 today to 41 by 2030 - one metropolis that stands out is Mexico City.
In spite of a population of 20 million people and some of the world's worst traffic, Mexico City has made it work. Eric Garcetti, the mayor of Los Angeles, visited the city in March to find out how to turn his own congested city into a haven for bikers. Efforts to get a system going have failed to get off the ground.
In Mexico, there was political will. The city provided a hefty initial investment - US$3,400 per bike, more than what was provided by Barcelona authorities - to have a docking station every 250 metres Given the size of the metropolitan area - 2,330 sq km - the programme covers only a fraction - 21 sq km.
Seattle, poised to launch a programme next month, faces a built-in hurdle. The home to Microsoft has a law requiring all cyclists to wear helmets, which history shows will sink its bike-sharing dream.
In Melbourne, Australia, the prospect of an A$185 (HK$1,335) fine for not wearing a helmet has led to rows of unused bikes. But in Mexico City, a law making helmets obligatory was repealed almost instantly and residents flocked.
"Mandatory helmets is a massive deterrent," Meddin says.
What makes cycling safer is having more bikers on the road, he says. The evidence would seem to support this. In London, the first fatality on the so-called "Boris Bike" - named after Boris Johnson, London's mayor - happened three years and more than 22 million rides into the initiative.
Reuters reports that, so far, there have been no fatalities among people using the 37 programmes in the US, led by the New York City programme sponsored by Citigroup.
For Seth Nemeroff, 40, a New York financial consultant, Citi Bike was a godsend. He left his pregnant wife at their apartment to attend a talk outside the city centre, only for his wife to go into labour at 6.45pm. He says in rush-hour traffic, the journey back would have taken 40 minutes, but it took only seven minutes on a Citi bike. Just in time to take his wife to hospital - by taxi.
"I'd have never made it otherwise," he says.
New York started the scheme six years after Paris, and three years after London. Like other American cities, it battled a culture and urban landscape built around cars. Yet in just over a year, more than 100,000 people signed up to use 6,200 bikes. Supply has not kept up with demand. At 8.30am, the racks outside Penn Station are often empty.
A key challenge for planners is how to bring the fleets of bikes to low-income communities. From New York to London, so far bikes are located in affluent areas where sponsors want to be seen.
Most European and American cities rely on sponsorship income and user fees. By contrast, in China, it's all public funding.
London doubled its prices last year, and Barclays Bank, which paid £25 million to brand the bikes with its logo and trademark blue, won't extend its five-year contract after it ends next year.
This raises the question of whether bike-sharing programmes, even when popular, can - or should - make money while serving the public.
Canada's Public Bike System, the supplier to New York and Washington, filed for bankruptcy protection in January, citing almost US$50 million in debt.
In New York, new investors are now being brought in to pay for an expansion.
Citi Bike's next operators - who plan to add bikes to Queens and untapped parts of Brooklyn - may increase the annual membership fee by almost 50 per cent, to US$140. New Yorkers living in public housing are entitled to a US$35 discount.
As debt-hit cities consider the financial viability of the schemes, the next generation of bikes is getting a test run in Copenhagen. They come with electric motors and GPS map navigation on computer tablets.
Each bike will cost Danish taxpayers US$7,600, but Morten Kabell, the city's deputy mayor who pushed for the programme, believes money should be no object. "If you want people to quit cars you need to offer them a quality alternative," he says.