Parts of the course will be made wider enabling more opportunities for athletes to pass, while new features have been added to increase the technical difficulty of the course.
With the main climb extended, riders will now cover 172 metres of climbing per lap. A new climb has also been added into the start loop, which will be used on the first lap of the races.
Elite athlete feedback
LOCOG Director of Sport Debbie Jevans said: 'These changes to the course have been implemented after feedback from the elite athletes following the test event and from conversations with the UCI.
'We are confident that the London 2012 course remains one of the most technically challenging courses at an Olympic Games, whilst we have ensured that it is as competitive as it can be by increasing the number of places where competitors can pass each other.'
Today also saw Essex County Council and The Salvation Army launch legacy plans for the Hadleigh Farm and Hadleigh Country Park site, including new and improved cycling trails and visitor facilities.