The Casse Déserte, says double Tour de France champion Bernard Thévenet, can only really be compared to the ‘moonscape’ of Mont Ventoux. The vast, middle section of the southern route up the Col d’Izoard marks it out as quite a different beast to the other big climbs in the Alps.

Most of them boast a lush, green, summer covering – picture the Heidi hills of just across the border in Switzerland. The Izoard, however, and the Casse Déserte in particular, bring something very special to the table.

‘It’s wild and empty,’ Thévenet tells Cyclist. ‘There’s nothing there – barely a plant or a tree among the rocks. And when you see photos of it in the newspapers or cycling magazines, it’s stunning. For photographers at the Tour, there’s nothing else like it – save, perhaps, for that top section of the Ventoux. But when you’re there racing, you simply don’t see it,’ he adds, referring to the tunnel vision of suffering, as well as the sheer volume of spectators who flock to the roadside whenever the Izoard appears on the Tour route.

The other, northern approach – nearly 20km uphill from the town of Briançon at an average of just under 6% – bears all the hallmarks of a typical Alpine climb, as do the lower slopes of the Izoard from the south. Starting at the town of Guillestre, the southern route takes around 30km to reach the top, with the first half taking in a steady and stunning climb through the Guil Gorge, against the flow of the River Guil, until you reach the start of the climb proper, where the D902 meets the D947.