A cycle hire scheme got under way today with London mayor Boris Johnson hailing it as "a new dawn for the bicycle in the capital".
Overlooked by the London Eye on the south bank of the River Thames, Mr Johnson was at one of the 400 central London docking stations where 6,000 hire cycles will be stored.
More than 12,000 people have signed up for the Barclays Cycle Hire project, which aims to generate up to 40,000 extra cycle trips a day in central London.
A total of 315 of the 400 docking stations - where bikes are taken and returned - were in use today and around 5,000 of the bikes were available.
Mr Johnson said today: "Londoners have awoken to a new dawn for the bicycle in the capital. Overnight, racks have been filled with thousands of gleaming machines that will transform the look and feel of our streets and become as commonplace on our roads as black cabs and red buses.
"My crusade for the capital to become the greatest big cycling city in the world has taken a gigantic pedal-powered push forwards."
To begin with, the scheme will be available to those who sign up for membership.
They will then receive a key which costs £3, with membership costs at £1 for 24 hours, £5 for seven days and £45 for an annual membership.
The first 30 minutes of any journey will be free, and the next 30 minutes will cost £1, with rising costs for journeys of more than one hour.
Casual users will be able to hire cycles around four weeks after today's launch.
Docking stations and hire bicycles will be available in Camden, City of London, Hackney, Islington, Lambeth, Kensington and Chelsea, Southwark, Tower Hamlets, Westminster and several of the Royal Parks.
London Assembly Green Party member Jenny Jones welcomed the scheme but said there were concerns that Mr Johnson needed to address.
She said: "The bikes should have locks and bigger baskets. A target date should be set for people to be able to use Oyster (travel) cards to pay for the bike hire.
"The scheme also needs monitoring closely to ensure that the cost is not putting low-income Londoners off using the bikes.
"Above all, the scheme should be expanded quickly, as we currently have only a quarter of the bikes which Paris now has and the scheme covers a much smaller geographical area."