Today more than 50,000 competitors will take part in a 100-mile road race on a route that starts in the Queen Elizabeth Olympic Park in east London, scene of last year's Games, before taking them into the Surrey countryside.
Rugby World Cup winner Matt Dawson, two-time Olympic rowing champion James Cracknell, former Olympic champion sprint hurdler Sally Gunnell and actor Gary Kemp are among the famous faces taking part.
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Tencho Hristov ignored warnings and got trapped between barriers at Roydon in Essex.
The 6km bike track will include 130m of the South Circular near Kew Bridge.
The unfortunate officer was taken to a central London hospital for treatment and his condition is not life-threatening.