The recent terror attacks in the UK have prompted police to carry out a review of security for what will be one of their busiest weekends in London.
Thousands of police officers will be on duty in central London
The Metropolitan Police is expecting more than one million people to turn out to watch the Tour de France.
Thousands more will attend the finals of the Wimbledon tennis tournament and the Live Earth concert at Wembley.
A Metropolitan force spokeswoman said "an appropriate policing plan will be in place".
In total, 4,500 officers will be on duty throughout the Tour de France start in London.
They will be assisted by 1,800 Kent Police and officers from the City of London Police and British Transport Police. A team of 45 French officers will also form part of the operation.
The Met spokeswoman said: "We have thoroughly reviewed the policing plans for all events over the coming days, including the Tour de France, to ensure that they are fit for purpose."
She said they anticipated more than 500,000 people turning out to watch Saturday's Prologue, the speed trial before the race, and "possibly more" for the first stage on Sunday.
The spokeswoman confirmed the review was in response to the recent attacks in London and Glasgow but said little had changed as "security was always a very high priority".
"There will be over and above the normal levels of police so we are confidents we can cope," she added.
Traffic will not be banned from central London during the event and police said a detailed plan has been drawn up to deal with overcrowding.