Col de l’Iséran, FRA

At 2,764 metres, the Col de l’Iseran is the highest paved mountain pass in the Alps. In Savoie it connects the high valleys of the Isère and the Arc as part of the Route des Grandes Alpes. Approach from the north and you have almost 50 kilometres of climbing ahead of you. What counts here is not steepness, it is sheer scale.

The Iseran at a glance

The northern approach from Seez near Bourg-Saint-Maurice measures 47.4 kilometres with around 2,050 metres of climbing, 4.2 percent on average, ten percent at the steepest. The average is misleading: there are flat sections and even short descents in between, and the real climbing sections are considerably steeper. Hors catégorie on length and altitude alone. At the top, 2,764 metres and usually a cold wind are waiting.

The climb from the north

The climb plays out in three acts. Act one: up the Isère valley towards Sainte-Foy, undulating with ramps of eight to ten percent between kilometres eight and thirteen. Act two: the galleries and short tunnels along the Lac du Chevril, then a long, almost flat stretch past Tignes to Val d’Isère. Eat, drink, breathe.

Act three: the final 16 kilometres from Val d’Isère. A constant six percent with short sections up to ten, in ever more open high mountain terrain. The trees are long gone, replaced by marmots and a ribbon of asphalt sweeping in big arcs towards the pass. The altitude works noticeably against your legs up here.

History and racing

The pass road was built from 1929 to 1937 and inaugurated on 10 July 1937 by President Albert Lebrun, completing the Route des Grandes Alpes from Thonon-les-Bains to the Mediterranean. The Tour de France arrived in 1938: Félicien Vervaecke was first over the top before Gino Bartali passed him on the descent and went on to win the Tour. In 1939 the Iseran hosted the first mountain time trial in Tour history, won by Sylvère Maes. In total the pass has featured eight times: 1938, 1939, 1949, 1959, 1963, 1992, 2007 and 2019. It was also planned for 1996, but snow intervened, the stage shrank to 46 kilometres and put Bjarne Riis in yellow.

The most memorable appearance came in 2019. On stage 19 a hailstorm and a landslide stopped the race beyond the pass, the stage was abandoned and the times taken at the summit of the Iseran. Egan Bernal had crossed first, took more than two minutes out of Julian Alaphilippe and pulled on the yellow jersey he would wear to Paris. Bernal also collected the Souvenir Henri Desgrange, awarded at the highest point of the Tour, here at the highest point it has ever been awarded.

Practical tips

The Iseran is a summer-only pass, usually open from June to October. With almost 50 kilometres of climbing, food is non-negotiable, and Val d’Isère is the last reliable stop. Even in August it can be single-digit temperatures at the top, so pack a wind jacket. The southern side from Bonneval-sur-Arc is the shorter, punchier alternative: a good 13 kilometres at around seven percent with sections above ten.

How does the Iseran compare?

The Galibier is the bigger Tour drama, the Iseran the bigger mountain. And the eternal rivalry with the Col de la Bonette resolves cleanly: the Bonette loop road does reach 2,802 metres, but the actual pass sits lower. The highest true pass of the Alps remains the Iseran. If you collect altitude the way others collect stamps, there is no way around it.

The Iseran ranks among the top 50 of our 100 climbs, on the 100 Climbs posters and on the compact 50 Climbs edition.

Is the Col de l’Iseran the highest pass in the Alps?

Yes. At 2,764 metres the Iseran is the highest paved mountain pass in the Alps. The Cime de la Bonette is higher at 2,802 metres, but it is a loop road above the actual pass, not a pass crossing.

Which side of the Iseran should I ride?

From the north (Bourg-Saint-Maurice) it is the grand voyage: 47 kilometres with flat sections and the galleries along the Lac du Chevril. From the south (Bonneval-sur-Arc) it is the compact mountain ride: a good 13 kilometres of constant climbing in high alpine terrain. The southern side wins on scenery, the northern side on history.

When is the Col de l’Iseran open?

Usually from June to October, depending on snow. In winter the pass road is closed and the high valleys belong to the ski areas of Val d’Isère and Tignes.