The start of the Tour de France in London, the first in the 104-year history of the world's greatest annual sports event, was hailed an outstanding success.

After car bombs, weeks of rain and a Tube derailment, the blazing sun and more than a million spectators came out to greet 189 top endurance cyclists from across the globe on Saturday.

The competitors rode a 7.9km time trial prologue past landmarks such as Big Ben, Hyde Park and Buckingham Palace to establish who will wear the yellow jersey in the first stage of the race on Sunday from London to Canterbury in Kent.

Britain's Bradley Wiggins, the Olympic pursuit champion, came fourth while Fabian Cancellara of Switzerland won the challenge in a blistering 8 min 50.74 sec.

The riders whizzed around the course in speeds of up to 44mph, far above the normal 30mph speed limit.

Crowds of six deep started building early Saturday morning as families arrived with foldaway chairs and sunglasses to claim the best spots long before the set-off at 3pm.

After waving off the first rider on Whitehall, London mayor Ken Livingstone said he was "amazed, astounded and very pleased indeed" by the colourful turn-out.

"Did anyone say that it would not be a success?" he said. "The only thing that has been more amazing is that after months of awful weather that the summer came out for it."

About 4,500 police officers guarded the event, assisted by 45 French officers.

"From a policing point of view this is a big weekend," said Assistant Commissioner Tarique Ghaffur of the Metropolitan Police.

"There is Wimbledon, the O2 and Live Earth. There is the severe terrorist threat so we have to be very cautious."

Nevertheless, Mr Ghaffur hailed the event a "significant success" in policing terms.

London's transport commissioner Peter Hendy added: "This is brilliant and we should do it again."

Transport for London (TfL) hopes the race will increase cycling among ordinary people, building on an 83% rise since 2000.

It fitted 11,000 bike parking spaces, mainly in Hyde Park, Green Park, Millbank and near the Albert Memorial.

Whitehall, Parliament Street and Victoria Embankment, will be closed throughout the weekend while most of the roads along the route will remain closed until 2100 BST.

Road closure will also include: Kensington Road (east of the Royal Albert Hall), South Carriage Drive, West Carriage Drive, Serpentine Road, Pall Mall, Pall Mall East, Haymarket south of Charles II Street, Cockspur Street, Strand, Trafalgar Square, Charing Cross Road south of Cambridge Circus and Northumberland Avenue.

On Sunday, the cyclists were due to depart from The Mall at 10.25am. A ceremony was to take place at Tower Bridge at 10.40am, followed by the rolling start of the 203km stage at the Meridian Line in Greenwich.

The race was expected to finish in Canterbury at around 3.30pm.

Hyde Park was to host a free cycling festival from 11am to 5.30pm, featuring races between more than 300 elite athletes and youngsters on a 3.5km section of the Tour de France Prologue course.