The “Secret” Road to Col de la Charmette. A Chartreuse Alps Loop


The Chartreuse Alps is the massif between Chambéry and Grenoble. It is home to the Grande Chartreuse – the head monastery of the Carthusian order.

It’s a great place for cycling col hunters with Col du Granier, Col de Porte, and Col du Coq probably the most “famous.” Click here for several Chartreuse Alps loops.

Col de la Charmette Tunnel

For this ride I was looking to see of it was possible to climb a tiny “road” up to Col de la Charmette. Leaving St-Laurent-du-Pont heading into the Gorges du Guiers Mort there is almost immediately a tiny, unsigned, unlikely looking road to the right. This is the start of the climb. See map at bottom for details.

After Chartreuse de Curière monastery the road is closed to cars (wooohooo) and no longer decently surfaced. It shouldn’t be descended on a road bike ….. and probably shouldn’t have been climbed on one either. Very rough at times. But it is fairly awesome.

I’ll let the video below explain the rest.

I forgot my camera so all photos are with my phone.

Half way to Col de la Charmette:

Col de la Charmette

The other side of Charmette is steep but a normal little road — I saw several cyclists. Next, I set off up into the Chartreuse …. first on a deserted, but challenging road to Col de Palaquit.

Col de Porte Col de Palequit Charmant Som

Here the route joins the quiet (but main) road to Col de Porte. At Col de Porte I had lunch (!!) and then headed left on a little road for another 6 kilometre climb up beautiful hairpins to Charmant Som.

Charmant Som

Note, the profile above for Charmant Som is for the principle road from Grenoble, I started higher and took a quieter road, and then joined up at Col du Palaquit. Both are great.

View from Charmant Som:

Charmant Som

From Charmant Som it’s completely downhill back to St-Laurent-du-Pont. The second half is through the fabulous Gorges du Guiers Mort. The tunnel sign was scarier than the tunnels. 🙂

Scary tunnels

This is a terrific loop. I was thrilled that it was passable by road bike. But next time I’ll bring my hybrid.

9.1 Awesome

The "Secret" road to Col de la Charmette is one of those special routes that while riding it you can't help but smile.

  • Views 8.5
  • Difficulty 9
  • Quiet / No Traffic 10
  • Fun Factor 9
  • User Ratings (1 Votes) 7.8

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Happiest while cycling uphill.


  1. We did this climb up the “closed” road a couple of years ago on a road/touring tandem bike with panniers. The road was completely dry then, and it wasn’t too hard to keep traction. In those conditions, you could certainly climb it on a road bike, although I would agree that descending it would be very sketchy. The lower section was the steepest, and that was all paved. It was an awesome adventure. See photo here:

  2. thanks for the pics Chris. You guys are incredible with the tandem ….. that road is so steep, especially early on. Yeah, agree, I caught the road early in season, wet, and lots of debris. As long as one isn’t too fussy, road bike is “ok” going up.

    Fun route.

  3. hi there,
    I’ve never used this road, only went up the col de la Charmette from the other side and backtracked.
    I know (have seen pictures) this side you climbed is really pretty, deserted and therefore quite, etc. But I think it is also important to stress that this is a forbidden road and that one can be fined for cycling/hiking there.
    I still hope to go at some point, but I thought, given others might want to follow suit…. well… one should know! There are lots of rocks falling down etc so it IS most definitely a dangerous area… avoid having picnic there 😉
    Do you agree?

  4. I don’t think it’s forbidden. It is closed to cars, but I saw no signs forbidding bikes …. and it is certainly open to hikers. There was some work happening when i was there fixing one section.

    No doubt there are some falling rocks, but I didn’t see it as dangerous at all.

  5. Pingback: Ten “Fun” Tunnels to Cycle in the Alps

  6. Hi, thanks to your blog I discovered this beautiful climb (Col de la Charmette). Climbing (beginning of June 2014) on a dry day is absolutely no problem with a race bike – descending would be a bit more ‘adventurous’ and is not recommended.
    The part where we climbed the Col de la Charmette via the infamous ‘route forestière’ can be seen from 8’35” in this video :
    Parts from the Gorges due Guiers Mort and climb/descent of Charmant Som can also be viewed in this video.
    Thanks for the tip !

  7. Just rode the “backside” of the Charmette earlier today with my son. Details here, including a few pictures this website is free to use if they like-

    As I point out in the blog piece, this road is easily done with any road bike (when dry and not muddy anyway), with the exception of the longer tunnel, where, even with a good light, it might be tough to pick a path around sharp rocks, and maybe just three or so other very short (less than 50 meters) sections. It’s a pretty amazing little road. I wouldn’t worry at all about the road being closed to bicycles; I didn’t see anything saying so, nor could I imagine a reason for doing so.

    Thanks for providing this website, which gave me the idea a couple years ago that this would be worth doing!

  8. C is right. The road is closed to all traffic including bikes. It is a 135 euro fine and there are patrols by the park guards.

    • Thanks. That’s a shame! Are you sure the sign said bikes? Sometimes the mopeds signs looks like bikes? The road was certainly closed to motor traffic when I was there.

      • Hi Will,
        Definitely all vehicles including bikes. I don’t know what the risk is but a policeman friend of mine was stopped. He wasn’t fined but had to turn around. The Forest Patrol (ONF) have police powers as do the park guards.

        It is a bit mad as you can do the road on foot but not on a bike.

        I guess the risk is limited.

        If you are back in the area I don’t know if you’ve seen that the route du Mortier from Grenoble to Autrans is fully reopen, at least to bikes.

  9. Did it today. Very nice climb. Steep at parts. I did it with the mountainbike, partly because of the lower gears I have on it. But was happy I took it around the stretch with the tunnels.

    The sign that forbids you to enter on bike is the famous circular one, white center with a red edge. So all vehicles forbidden, including bikes. Also the barrier has a sign “sauf ayant droit”, only with permit.

    Anyhow, I decided to take the risk. Was even passed by a patrol car just before the barrier, and they didn’t stop me. So it’s a risk, but acceptable and the reward is big.

    Thanks Will, for pointing this one out.

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