The Tour Divide is the world's longest off-road race and the pair of adventurers are aiming to break the course record in 17 punishing days.
The duo, both biking novices, will be seen tackling the course – which involves climbs equivalent to scaling Mount Everest seven times from sea level – in a BBC 2 series later this year.
Previous challenges undertaken by the duo have included crossing the Atlantic in a rowing boat, for TV series Through Hell and High Water. Last year, they endured a gruelling race to the South Pole which formed the series On Thin Ice.
Neither Cracknell, a double Olympic gold-winning rower, nor Fogle has had any serious mountain bike experience.