From the Lac du Chambon dam, at 3,425 ft (1,044 m), to the Col de Sarenne at 6,558 ft (1,999 m), it’s 8 miles (12.8 km) at an average 7.5% and 3,130 ft (954 m) of climbing. It’s the quietest climb in the Oisans, and the most beautiful way to reach Alpe d’Huez.
What the climb is like
- The first mile. Right after leaving the Lautaret road at the dam, you hit the hardest part: 12-15% ramps up to Mizoën.
- Mizoën to Clavans-le-Bas (about 2 miles, or 3 km). An easy stretch at 3-5%, then almost 1.2 miles (2 km) at 9-10% toward the Besse turnoff.
- Clavans-le-Bas to Clavans-le-Haut (about 1 mile, or 1.5 km). An almost flat breather at 2-3% between the two hamlets.
- The last 4.3 miles (7 km). Now in the high valley, with nothing but pasture and mountains, the grade settles between 8% and 10%, with the odd 13-14% ramp. No villages and no shade until the col.
A note on the numbers
Climbfinder gives 12.8 km and 958 m (7.5%), and cols-cyclisme 12.8 km and 954 m (7.45%). CyclingCols measures from Le Clapier, at the bottom of the valley, and gives 13.7 miles (22 km) at 5.7%, adding the Lautaret road up to the dam. The maximum grade is between 12.5% and 14% depending on the source.
History
The Sarenne became famous in 2013, when the Tour de France climbed Alpe d’Huez twice in the same stage and used this col to link them, via a narrow, technical descent. CyclingCols lists Tejay van Garderen as first over the top that year, and a new appearance in the 2026 Tour.
When to go, water and traffic
The road is closed in winter and usually opens late, once the snow is gone. Traffic is minimal, often just cyclists. Fill your bottles in Mizoën or Clavans; there are no services at the top until Alpe d’Huez. Bring a wind jacket for the descent.
What gearing to use
On a 34x30 or 34x32 you’ll get up without trouble. At 3 W/kg (watts per kilo of body weight) and 159 lb (72 kg), you’ll ride about 6.2 mph (10 km/h) on 9%, around 69 rpm on a 34x30; on the 13% ramps you drop to 4.3 mph (7 km/h). Check it in the gear calculator.
Frequently asked questions
How long does it take to climb the Col de Sarenne?
A 159 lb (72 kg) rider on a 21 lb (9.5 kg) bike takes about 1 h 06 min at 3 W/kg (216 W), 1 h 18 min at 2.5 W/kg and 51 min at 4 W/kg. Work out your own time with your weight and power in the calculator on this page.
How does the Sarenne connect to Alpe d'Huez?
From the top you descend toward the Alpe d'Huez altiport. So you can climb the Sarenne and descend the 21 hairpins, or the other way around, as the Tour de France did in 2013.
Is the pavement on the Sarenne good?
It's a narrow mountain road with rough pavement in places and no guardrails on many bends. Descend it with care.