Cycles can ride through a 12km traffic-free route in central London
Cyclists have taken to the streets of central London as large parts of the city became traffic-free for a day.
The Freewheel event, an annual day dedicated to cyclists, was expected to attract 45,000 people.
A 12km route has been made available for riders who can cycle through Buckingham Palace, Trafalgar Square, the Tower of London and Admiralty Arch.
Olympic winners Chris Hoy, Victoria Pendleton, Ed Clancy, as well as Mayor Boris Johnson joined cycle enthusiasts.
The route begins near Buckingham Palace and ends in Victoria Park, crossing the Tower of London.
The entire route remained closed to motorised traffic until 1730BST on Sunday.
Olympic gold medallist Chris Hoy said: "It's fantastic to be involved with a day that encourages more people to get on their bikes around London. Personally I can't wait to cycle down the Mall."
Mr Johnson said: "The aim of Sunday's event is to celebrate cycling and encourage people in London to use it as a way of getting around and making the most of the city.
"I'm sure that the involvement of such fantastic cyclists from British Cycling, whose achievements were cheered on by millions of us during the Beijing Games, will only serve to inspire more Londoners to get involved and take part in this great free event."
This year organisers added a large rest area in St James's Park where participants can take in some of London's best views.
The event offers a variety of shorter routes into the city for young or new cyclists to try out.
The day includes entertainment, and organisers say there will be a carnival atmosphere.
Last year - the event's first - drew 38,000 cyclists onto the city's streets.