23.4
PDI
8.2 mi
DISTANCE
3,203 ft
GAINED
7.4 %
AVG. GRADE
FULL CLIMB STATS
INTRO
Col de l'Iseran is the highest paved pass in the Alps, and the southern approach from Bonneval-sur-Arc is its wildest and most beautiful side. From the hairpin above the village, the D902 climbs 13.2 km (8.2 mi) and 976 m (3,203 ft) at an average grade of 7.4% to the 2764 m (9,068 ft) summit - short by big-Alpine standards, but steep, high, and relentlessly scenic from the first kilometer to the last. There are two primary routes to the top, one from the south here in the Maurienne and one from the north out of Val-d'Isère.
The climb opens with a giant switchback above Bonneval and four solid kilometers at around 8% before bending into a flower-filled meadow along the Ruisseau de la Lenta - a brief breather that even dips downhill for a few hundred meters. Then the road turns and climbs hard up a series of hairpins and along a sheer cliff face that is one of the most dramatic (and, for nervous drivers, most unnerving) stretches of road in the Alps. After a short tunnel the grade eases for a while before a steep final push, past glacier views, to the col and its small stone chapel, Notre-Dame-de-Toute-Prudence, completed in 1939.
The Tour de France first crossed the Iseran in 1938, and in 1939 held the race's first-ever mountain time trial from Bonneval over the pass to Bourg-Saint-Maurice, won by Sylvère Maes. As of 2023 it had been included eight times, most recently in 2019, when Egan Bernal led over the summit before hail and a landslide stopped the stage - times were taken at the top, and Bernal rode into yellow. The road is open only in summer: it reopened on June 12 for 2026 and typically closes in early November, sooner if snow comes early. At this altitude, check conditions before you go with our Weather tool.
PLAN YOUR ROUTE
We've partnered with Sherpa-Map.com to bring you the best route planning tool. With a PRO Membership you can use this climb as a reference when creating your route. Col de l'Iseran from Bonneval-sur-Arc climbs 13.2 km (8.2 mi) from 1789 m (5,870 ft) to the 2764 m (9,068 ft) summit, gaining 976 m (3,203 ft) at an average grade of 7.4%.
The first 4 km (2.5 mi) are steady and stiff at about 8%, looping up above Bonneval before the road enters the meadow along the Ruisseau de la Lenta, where it flattens and briefly descends. From the hairpin at the end of the meadow, the next 4 km (2.5 mi) up the cliff-side hairpins average roughly 8.3%. Beyond the short tunnel, the grade drops back for a couple of kilometers before the hardest ramp of the day about 2 km (1.2 mi) from the top.
The steepest 0.5 km (0.3 mi) averages 11.5%, the steepest kilometer 11.1%, the steepest 2 km (1.2 mi) 9.9%, and the steepest 5 km (3.1 mi) 7.7%. Kilometer markers line the road the whole way, showing the distance to the summit, the current altitude, and the average grade of the next kilometer.
Roadway: The D902 is paved the entire way and generally in good summer condition, but it's a high-mountain road in every sense - narrow in places, with long exposed sections above steep drops, a short tunnel in the upper half, and the usual frost-heave patching. The pass is closed in winter; for 2026 the road reopened on June 12 and normally closes in early November, though snow or heavy rain can close it at short notice - check the Savoie department's road information before setting out.
Traffic: The Iseran is part of the Route des Grandes Alpes, so expect a steady stream of cars, camper vans, and especially motorcycles on summer days, heaviest in July and August - an early start gives you the quietest road. Each June, the Iserane event closes the road to motor vehicles for a morning so cyclists can ride it in peace.
Parking: Cars aren't driven through Bonneval-sur-Arc's old stone village - all parking sits around its edges along the D902. The Parking de Pierre Fendue is free and open year-round, and there are other free municipal lots at the village entrances, a short roll from the start of the climb.
Provisions: Stock up in Bonneval-sur-Arc before you start. The village has a few shops and restaurants, and the dairy cooperative's shop in the old village, beside the church, sells Beaufort and the local Bleu de Bonneval - worth a stop after the ride. There are no reliable services on the road between Bonneval and the summit, so carry enough water and food for the full climb.
Gear: Low gearing helps on the cliff-side hairpins and the steep finish, and you'll be riding above 2500 m for the final few kilometers, where the air is thin and the weather changes fast. Bring a windproof jacket, gloves, and a warm layer for the descent even in midsummer, plus a rear light for the short tunnel.
Before heading out on any cycling adventure check out our Things to Bring on a Cycling Trip and use our interactive check list to ensure you don't forget anything.
Bonneval-sur-Arc is one of the "Plus Beaux Villages de France," and it earns the title: a tight cluster of stone houses under heavy lauze-slate roofs, with farm buildings deliberately moved out to a separate agricultural zone to keep the old village intact. Give yourself time to wander it on foot before or after the ride.
A few kilometers up the valley, the hamlet of L'Écot - a filming location for the Belle et Sébastien films - is reachable by road or on foot and offers a glimpse of traditional mountain life at the edge of the Vanoise National Park. The Iseran's steep southern descent also enters the park, the oldest in France.
For a longer, grander day, start from Lanslebourg-Mont-Cenis and ride up the Haute Maurienne valley to Bonneval before the climb proper begins - our "Start of longer route" Street View below shows that start point. Descending the far side to Val-d'Isère opens up the Tarentaise's big climbs, making the Iseran a natural link on a multi-day Alpine trip.
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