In the skyline of France's Provence region, Mont Ventoux culminates at 1,909 metres. Each year, its steep slopes are the setting for an epic stage of the Tour de France cyling race. The bald mountain fascinates professional and amateur cyclists alike. The most determined of them even attempt the "Nutters' challenge": climbing Mont Ventoux three times in one day on the three different roads to the summit. We went to meet some of them.