The route
150.8 km from Courmayeur to Chamonix, climbing 9,313 m, starting at 11:50 pm.
Drawn with a pen, line by line
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Indicative figures computed by Plotrek on its illustrative route, with altitudes from a terrain model. They may differ from the organiser's.
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TDS follows the old paths of the Dukes of Savoy, from Courmayeur to Chamonix, with one of the most intense climbs in the massif. It starts at 11:50 pm, almost midnight.
The trail climbs straight to Col des Chavannes, the highest point of the course, at 2,581 m, before dropping via the Petit Saint-Bernard pass.
It passes Bourg-Saint-Maurice, then climbs to Passeur de Pralognan, before dropping toward La Gittaz.
The trail then passes Hauteluce, Le Signal and Col de Tricot, before Les Houches and the finish in Chamonix. Runners have up to 44 hours and 55 minutes to finish.
Paths and places: © OpenStreetMap contributors. Altitudes measured on the route.
03 · Your poster
The relief of the course, from Courmayeur to Chamonix, takes shape as contour lines: our pen plotter draws it with a pen, line by line. Your finisher name and time go in the title block, in A4, A3 or A2.
Shipped from our workshop in Le Bouscat
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Updated Route and text: Plotrek workshop (Fabrice Jolivet)
The organiser announces 150.8 km and 9,322 m of elevation gain for the 2026 edition. Plotrek's illustrative route, redrawn on OpenStreetMap paths, measures 150.8 km and 9,313 m of gain. Start: Courmayeur; finish: Chamonix; on the way, La Gittaz at km 74.1. The elevation loss measured on this route is 9,497 m.
44 hours 55 minutes for the 2026 edition, according to the organiser's website, read on 17 September 2026. That is the time allowed to cover the announced 150.8 km. Start: Courmayeur, at 11:50 pm. The time limit can change from one edition to the next; the organiser's rules prevail.
Col des Chavannes, at 2,581 m, at km 20.6 of Plotrek's route. The organiser gives a maximum altitude of 2,589 m for the 2026 edition. The high point lies between two landmarks of the course: Courmayeur (1,224 m, km 0) and Passeur de Pralognan (2,534 m, km 62.1).
1,547 m of elevation gain in one go, from km 50.1 to km 59.6 of Plotrek's route. No other climb on the 150.8 km course is as long. Average gradient of this section: 16.3%. It accounts for 17% of the route's elevation gain. Altitudes measured on the route, with a terrain model.
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