Key roads through the city will be closed to motorists, allowing participants in this year's London Freewheel event to cycle unhindered past landmarks including the Tower of London, London Eye and Buckingham Palace.

Mr Johnson said: "Cycling is a fantastic way to get around the city and, to show people just how enjoyable it can be, on 21 September cyclists of all ages and abilities can enjoy some of London's most famous sites by bike on a special car-free route.

"There are lots of Londoners who own bikes that aren't using them regularly, so hopefully this event will remind people what fun it can be."

It is estimated that 1.1 million Londoners have access to bikes but rarely ride them. London Freewheel is part of the Mayor's Summer of Cycling, which aims to encourage Londoners to experience the city on two wheels.

Last year's inaugural event saw more than 40,000 people take part. This year, "hubs" will be set up from 8am at Clapham Common, the Emirates Stadium, Ravenscourt Park and Victoria Park for participants to gather and prepare for the ride. Cyclists with less road experience can follow members of the London Cycling Campaign from the hubs to the main route, while marshals will be stationed at key junctions to point people in the right direction.

A shorter course for cyclists less able to complete the main 12km route will also be marked out.

Vintage bikes and mobile sound systems will be among attractions to keep riders entertained, while a Sky Sports zone in the Mall will provide a focal point for cycling enthusiasts.

Those wishing to attend are encouraged to register in advance and will receive regular email updates.

Click here to view the route of the Freewheel Event.