Above Bardonecchia, Colle del Sommeiller climbs toward one of the highest points in Europe reachable by a carriage road — an extraordinary adventure spanning both asphalt and high mineral mountain terrain.
An ascent through two worlds
From Bardonecchia, it’s about 26 km for nearly 1,700 m of elevation gain up to the summit, at 2,993 m (up to 3,009 m depending on the source). Only the first 6 kilometers are paved; the rest turns to gravel track, then scree as the climb approaches the pass.
A road built for a ski glacier
Built between 1963 and 1965 to enable summer skiing on the Sommeiller glacier, this road bears the name of Germain Sommeiller, the Savoyard engineer behind the Fréjus rail tunnel that begins just below. It runs through the Rochemolles valley before climbing toward a turquoise glacial lake at the summit.
How to approach the ride
A gravel bike or mountain bike with wide tires is essential once the paved section ends. Many cyclists choose to stop before the summit if late-lying snow or the state of the scree track makes the final stretch too risky — the ride remains fully rewarding even without reaching the full 2,993 m.
When to climb it
July to September only: the window is short, with snow able to linger or return early on this very high-altitude route.
Good to know
The summit is home to a strikingly turquoise glacial lake, a visual reward for cyclists who push the ascent all the way to the top of the scree track.
