Paris is one of Europe's most congested cities, but now officials may have a new weapon to combat the problem - free bikes. The city have set up an initiative called "Velib" and wheeled out 10,000 distinctive grey-green bikes which registered users can pick up and take for a spin. To access the bikes, riders purchase an access card - one-day costs 1 euro, a weekly card is 5 euros or an annual card is 29 euros. Armed with a card riders can enjoy the first half-hour for free, and then a rising supplement is charged for each additional half-hour. The idea is that most people should be able to get where they need to go within the free half an hour and the rising cost penalty should keep lots of bikes in circulation. There are already 600,000 registered riders and 750 bike pick-up and drop-off points along Paris's 370 km of cycle paths; by the end of the year the city aim to have 20,000 bikes in service and nearly 1500 pick-up points. But not everyone's enamoured with the new initiative. Taxi drivers, perhaps not surprisingly, are grumbling about having to avoid cyclists enthusiastically pedalling the wrong way up one-way streets, and pedestrians are having to dodge bikes that have invaded the pavements. And human nature has also created something of a problem with supply and demand - lazy Parisiens are picking up bikes at the tops of hills, coasting to their destination and then taking the metro back!