The Col de l’Iseran, the high point of the Route des Grandes Alpes at 2,764 m, is one of the most iconic road giants in the French Alps — a climb through an almost lunar high-mountain landscape in its final kilometres.
The profile from Val-d’Isère
From Val-d’Isère, it’s 16.2 km for 940 m of climbing, averaging 5.8% — a generally steady profile made hard by the already-high starting altitude (1,850 m) and the thinner air of the final kilometres. The road first winds through pasture around Val-d’Isère before rising into a mineral landscape, nearly devoid of vegetation past 2,500 m.
The summit, with its small chapel and 360° panorama over the Vanoise glaciers, marks one of the highest points ever crossed by the Tour de France.
How to approach the ride
Altitude is the main limiting factor on this climb: perceived effort rises noticeably above 2,000 m for the same power output, which calls for adjusting pace from the start rather than discovering it partway up. A light gear helps maintain a steady cadence over the duration without burning out early.
Alpine weather at this altitude can turn quickly: snow is possible even in midsummer, along with strong wind and a marked temperature drop at the summit. An extra warm layer in the back pocket is never overkill, especially for the descent.
When to climb it
The road is closed by snow for much of the year and typically opens only between late May and late June depending on snowfall — one of the last major Alpine passes to reopen each year. The ideal window runs from late June to September, and checking road conditions is strongly recommended before heading out outside July-August.
Good to know
Val-d’Isère, a major winter sports resort that converts to a hiking and cycling base in summer, has a wide choice of accommodation and direct access to other major climbs on the Route des Grandes Alpes for extending the stay over several days.
