Oisans is a paradise for climbers... and a terrain of suffering for anyone looking for the ultimate challenge. Between the high-altitude giants, double-digit walls and long, endless ascents, what are the hardest cycling cols in the Oisans Here is our ranking, from very hard to extreme.
How do you measure the difficulty of a mountain pass?
Difficulty is not just about the gradient. It combines the length, the average percentage, the steepest passages and the’altitude (the air becomes thinner above 2,000 m). To compare objectively, we rely on the index Bicycle, displayed on each col sheet, which synthesises these parameters into a single figure.
1. The Galibier from Oisans, the endurance test
By its length and altitude, the Col du Galibier from Bourg-d’Oisans it is a real feat of endurance: over 45 km of cumulative climbing along the Romanche and the Lautaret, up to 2,642 m. The difficulty comes as much from the distance as from the lack of oxygen in the final stretch.
2. The Col du Sabot, the high-altitude wall
One of the highest road passes in Isère (2,100 m), the Col du Sabot It covers nearly 17 km at an average gradient of 8 %, with a slope that never lets up and total solitude high above Vaujany. A little-known test of one’s mettle.
3. Cross of Iron, the long, implacable one
Hors catégorie over nearly 27 km, the Col de la Croix de Fer features an irregular profile, broken up by short descents that break the rhythm and make the effort more treacherous than it seems.
4. Villard-Notre-Dame, the wild wall
Most stiff of all : Villard-Notre-Dame climb up to 17 % over its 100 hardest metres, on a narrow road punctuated by unlit tunnels. Short, but brutal and technically demanding.
5. Oz-en-Oisans, the express slap
Proof that a climb doesn't need to be long to hurt: the direct ascent of’Oz-en-Oisans It averages nearly 11 % over 5.5 km, without a single flat stretch to catch your breath.
Extreme warnings
The Lake Besson, which extends Alpe d'Huez up to 2,070 m, and the adventurous Col de Solude (mixed route to be done on a gravel bike) complete this panorama of the region's toughest climbs.
Frequently asked questions
What is the steepest mountain pass in Oisans?
Villard-Notre-Dame, with sections reaching up to 17 % on the toughest 100 metres.
What is the highest mountain pass in the Oisans?
The Col du Galibier (2,642 m); the Col du Sabot (2,100 m) is one of the highest road mountain passes in Isère.
How do I know if a collar is too stiff for me?
Compare the FIETS index and the average gradient on each fact sheet, and progress step by step using our guide which mountain pass to climb according to your level.
Ready for the challenge? Find all the profiles and the level of difficulty on the Oisans mountain passes page.