Colle del Sommeiller


At 2,993 metres, Colle del Sommeiller is one of the very highest roads in Europe.

There is a great sign at the very start with various warnings, that calls the road “marginali.” Only the first 6 kms are paved (badly), and the surface for the remaining 20 kms can be rocky and challenging. But what a fun climb!

Surprisingly, it’s rarely ridiculously steep.

From Bardonecchia, the start can be tricky to find. See map below, or follow signs to “Rochemolles.”

At the village of Rochemolles, the paved road ends. A very rough, rocky road immediately hairpins up. And the fun begins. As an added bonus, after 10 kms or so, there is a nice dam / alpine lake at 1974 metres altitude.

Lago di Rochemolles

The pass is named after Germain Sommeiller, the Savoyarde chief engineer of the construction of the 13.7 km Fréjus railway tunnel under the Alps (opened in 1871) which starts exactly at the beginning of this climb. According to the sign at the summit, historically, the pass was called Col d’Ambin.

After the lake, the road soon climbs to a little plateau and the Rifugio Scarfiotti. It is like an amphitheater here. Big mountains on three sides. A little like Cirque de Gavarnie, or Cirque du Fer-à-Cheval. Usually the road would end here, but ahead was a series of unlikely hairpins that climbed up to the next valley. Amazing:

only the top hairpins fit in the photo

Occasionally, looking ahead, it was difficult to even guess where the road was heading. After these hairpins, the road winds through a deserted valley getting ever deeper into the mountains.

Finally, a few kilometres from the top, there is another series of huge hairpins as the road gets really high. The surface is difficult here, but the environment is stunning.

Approaching Colle del Sommeiller
Final Stretch

At the summit is Lago di Sommeiller. The sign (dubiously) claims it is the highest lake in the Alps. The water level is very low at the moment, the lake is often several times larger.

Lago di Sommeiller
The pass is after the road barrier and a touch behind the lake. Since it is at 2993 metres, I — of course — had to climb higher with the bike to ensure getting above 3,000 metres.
Glacier du Sommeiller
The road was formerly used as access to ski lifts allowing summer skiing on the Glacier du Sommeiller. This stopped in 1980 due to the declining glacier, and the impracticality of the road.

A nice, quiet day in late September was the perfect time to attempt this truly incredible road. Cycling author Daniel Friebe told me this climb was the “Holy Grail.” Yep.


9.6 Awesome

It's not easy to get above 3,000 metres, but it's certainly fun.

  • Views 9.5
  • Difficulty 9.5
  • Quiet / No traffic 9.5
  • Fun Factor 10
  • User Ratings (49 Votes) 5.6

Happiest while cycling uphill.


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  7. Hi Will,
    Do you have any thoughts on the possibility to get down at the French side?
    With strava route builder it looks like there is something (yellow dotted line) just after the border.
    But the internet is quite silence about cycling above le Planay (from Bramans).
    Have you had a look over the edge at the other side?

  8. Hi Will, the “Holy Grail” looks tremendous! Thank you for detailing it and so many other fabulous climbs. I use your site extensively to explore lesser known parts of the mountains. A quick question for you: When you say the Sommeiller is “rough” and best done with a mountain bike, I’m wondering how difficult it would be on a cross or gravel bike with, say, 40c tires. For reference as to what I will tolerate and my ability level on tricky terrain, in September 2018 I rode Strada dell’Assietta and surrounding roads to Gran Serin and other peaks on a road bike with 28c. Not the perfect choice but doable, no problems. On a scale of 1 to 10, how rough is Sommeiller? I hope to do this September 2019. Thanks very much.

    • The quality of the roads change over time of course …. but I’d say it’s no worse than Assietta. As I always say, it’s the long descents that make mountain bikes more perhaps fun. I did have a friend recently “complain” about how rough Sommeiller was this year (I haven’t been there in a while. But if you were OK on Gran Serin, I’d bet you’ll be fine on Sommeiller.

    • Chris I rode both Sommeiller and Gran Serin in August this year on a gravel bike with 38mm tyres. I’d say the decent from Sommeiller and from Gran Serin to Colle delle Finestre are similarly rough. I found both fully rideable but quite rough descending, fingers numb by the time I got down from the top. This was partly due to having cold hands while riding up combined with the long rough descent. I’m planning on going back to the area in 2019 and considering taking a mtb or fitting 50mm tyres to my gravel bike to enjoy the descents a bit more. Don’t worry though it’s definitely rideable with 40mm tyres on a gravel bike. Enjoy!!

  9. Love your blog will. Went up gravel roads to jafferau, bonette, parpaillon and sommelier among others on a trip to Alps this year and got lots of great info (and inspirational pictures) from your blog.

    I went over the other side of sommelier and can configure RM it’s all hiking trail. At one point I lost the Trail and ended up on the edge of a waterfall! Ended up taking 5 1/2 hours to get down to the other side (I was on 38mm tyres on cross bike).

  10. Patrick Evers on

    I am planning a loop tour in this area starting in Torino this september. Mostly looking for gravel roads. I think I want to include the Sommeiller. I want to thank you for your inspiring blog. Truly one of the best there is!

  11. Klemen Zupanec on

    How crazy doable is to reach it with a road bike (23 mm tires) ? I’m looking everywhere to find if anyone did that. With MTB is almost everything possible, but with a road bike could be unachieveable goal.

  12. Hi Will, let me start by saying that your blog is amazing. It’s truly inspiring for those out there who share the same passion! Next year I am planning my first gravel adventure and I am thinking of heading to Susa. Colle del Sommeiller, Finestre and Strada Assietta are on the shortlist among others. What would be the ideal period for this adventure? I see most people referring to August and September. What is your experience?

    All the best and please do keep blogging!

    • Hi Kevin, I think July – September is the correct answer. June might work, but some of these roads are very high and obviously not ploughed so you might run into unpassable snow in June. October would sometimes be possible.


  13. I have been to the Colle del Sommeiller last august. Amazing ride. I was glad I took my MTB imstead of my gravelbike. They were also building some kind of shelter/hut on the Colle del Sommeiller.

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