The rise of public cycling schemes is a boon for travellers, writes Brigid Delaney.
From Barcelona to Paris, European cities are becoming greener with the expansion of low-cost bicycle schemes.
Paris's Velib program, with its 20,000 bicycles, has proved wildly popular with tourists and locals.
The scheme, launched in July 2007, provides racks of heavy-framed bicycles around the city and all you need to access them is a credit card with a chip.
A EUR150 ($297) deposit is held in case you lose or damage the bike. It is free for the first half-hour and costs EUR1 for an additional 30 minutes, EUR2 for another 30 minutes and EUR4 every 30 minutes after, making them cheaper than the Metro and more efficient than crossing the city on foot. When you reach your destination, the bike can be returned to one of about 750 Velib stands around the city.
So popular is the scheme, the bikes were rented out 24 million times in the year to June last year. Nearly 130,000 people use them a day.
Other cities have launched their own low-cost bike schemes, including Lyon and Rennes in France, Pamplona in Spain and Dusseldorf in Germany. Cities previously considered unfriendly to cyclists - with their narrow streets and aggressive drivers - such as Rome, have successfully trialled schemes.
The initiative started in cycle-friendly cities such as Copenhagen, where old bikes were scattered around, before moving to coin-operated bikes and now to smart technology, which is often sponsored by companies in return for advertising on the bicycle.
In Germany and Austria, members receive a text message with a code to unlock the bikes, with a fee debited from the riders' bank accounts. In Barcelona, users buy a yearly membership for about EUR24. The first 30 minutes are free, with a charge of 30 cents for each subsequent half-hour.
Such is the success of the program there, bikes in popular places (such as near stations) are often unavailable in peak hour, while some users have had trouble parking their bikes as all the central docks are being used.
Paris cyclists reported similar problems, with many riding down hills and using public transport to climb them, resulting in a surplus of bikes at the bottom of places such as Montmartre. The French Velibs do not come with helmets, so bring your own if you have safety concerns.
Berlin, Frankfurt and Cologne have a scheme known as Call A Bike, where you register online (callabike.de). You are given a number and charged EUR5. You then call the number to receive a code to release a bike from its dock and phone the centre when you have finished to say where you have left it.
Some of the schemes exclude tourists who haven't set up accounts or registered. But those in Paris and Lyon admit anyone with a credit card.
Not all free or low-cost bike schemes have worked. Cambridge in England started one in the 1960s and revived it in 1993 - only to find that all 300 bikes were stolen on the first day.
A free scheme for London is being considered by bike-riding Mayor Boris Johnson.