Kelly Brook and Mayor Boris Johnson joined the participants
Tens of thousands of cyclists rode in central London, which was closed to traffic for the day, as part of an annual cycling event.
The 15km route began at Buckingham Palace and went through Victoria Embankment up to Tower Hill, covering the Square Mile.
The British Cycling event began in 2007 as the London Freewheel and is now called the Mayor of London's Skyride.
Mayor Boris Johnson and actress Kelly Brook set the cyclists off.
Olympic medallist Sir Chris Hoy and TV presenter Gethin Jones also hopped on to their bikes for the event.
Similar events have been held in Manchester, Glasgow, Leicester and Hounslow, west London.
Less confident cyclists
The roads were open for cyclists only between 1000 BST and 1600 BST.
Speaking about proposals to make motorists legally responsible for accidents involving cyclists the mayor said: "We need to make sure that cyclists are treated with respect and that they treat other road users with respect as well.
"The single biggest deterrent to people getting on their bikes is that they feel nervous."
Sir Chris said: "Cycling has something for everybody.
"It's not just going round the velodrome at break-neck speed."
Participants were asked to recount their experience through video blogs which were uploaded and displayed on a video wall during the day.
Ian Drake, chief executive of British Cycling, said: "We are trying to get one million more people cycling by 2013."
Transport for London said the event was meant to encourage less confident cyclists and their families to see London.
About 50,000 cyclists took to the roads for the event last year, organisers said.