La Marmotte course.
After 10 kilometers from the start in Bourg d’Oisans, the course hits the road to the Col de Glandon. In some editions the Croix de Fer is added, but that is basically the same climb except for the last 2 to 3 kilometers. The Col de Glandon is no less than 21.3 kilometers long at an average gradient of 6.9%. About halfway through the climb there is a flat stretch and even a short decline after a small mountain village. but this relief is only short lived before the road goes up steeply again. The climb can therefore be divided into two parts, whereby you are actually constantly facing a gradient of 7%-8%.
After reaching the top of the Glandon, the descent down the other side is neutralized. This was imposed some years back after too many accidents started to happen on the narrow, high-risk descent. Down in the valley, the time keeping is started again and the course continues through a wide valley for about 20 flat kilometers before the start of the climb to the Col du Télégraphe. This col is only 12.1 km long at a gradient of 7.1% but the descent after the summit is only about 4 kilometers before the climb to the legendary Col du Galibier starts. That is why you can also see the Télégraphe and Galibier as one long climb, which in all fairness it actually is.
The Galibier is a real killer with 17.5 km and a 6.9% average. It starts from Valloire in a pleasant way, but the last 7 kilometers are constantly above 8% and also way above an altitude of 2000 meters. After reaching the top at no less than 2642m you will almost certainly have suffered from the altitude. And weather conditions can also become a big factor here. From the Galibier it is a short, steep descent to the Col de Lautaret. From there, the road is much broader and brings you in a long a relatively straight descent back to Bourg d’Oisan at the foot of the Alpe d’Huez.
Then finally, after more than 160 kilometers, you hit the bottom of the mythical Alpe d’Huez climb. Just like the Galibier, this climb provides little shelter, but it at least it sits at a much lower altitude. Although that can also make is a very hot climb. This climb to the Alpe provides the last 1000 vertical meters with an average percentage of 8% over 14 kilometers. Especially the first 4 kilometers are very hard with percentages of 10/11%. After 177 kilometers and 5368 vertical meters you will be awarded eternal fame as the finisher of La Marmotte at the top of the Alpe d’Huez.