Thursday's stage 17, between Pau and the top of the Col du Tourmalet, is expected to prove decisive in the 2010 Tour de France.
The stage, which covers 174km (108 miles)
, involves 3,611m (11,847 feet) of climbing over three major mountains, finishing atop the Tourmalet, which towers at 2,115m.
Last Sunday, the BBC's Alex Murray joined 10,000 other amateur cyclists to find out what it is like to ride a stage of as part of the
Etape du Tour
event, and took a small video camera with him.
The professionals are expected to take five hours to cover the stage, but it took Alex 10 hours and 43 minutes, with a few stops to film.