Chris Boardman, Former Olympic Cycling Champion

Professional cyclists are phenomenal athletes who specialise in suffering. Big races like the Tour de France push them to the very limits of human endurance. What makes them do it? In recent years, the sport has been mired by drug cheating - can it change its tarnished reputation? Stephen Sackur speaks to retired Olympic champion and world record breaker Chris Boardman. What does one of cycling's great innovators make of the sport today?