British Olympian Will Clarke explains what it takes to win a triathlon on the London 2012 Olympic course in Hyde Park.
Hyde Park Triathlon
live on the BBC.
Elite women's race live on Saturday 1300-1515 BST on Red Button & the BBC Sport website (UK users only).
Elite men's race live on Sunday 1500-1800 on BBC 2, Red Button & the BBC Sport website (UK users only).