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The lake below the Cormet de Roselend, under green mountains, with pines, a chalet and a track on the meadow above the water
Thomas MARCHAND / Unsplash

TDS course map, aid stations and cutoffs

Courmayeur to Chamonix the long way round, through the Beaufortain, billed as 145 km with 9,500 m of climbing.

2027 dates not announced yet, usually in August Courmayeur, Aosta Valley, to Chamonix

The name is short for Sur les Traces des Ducs de Savoie, and the route links the Aosta Valley to the Savoie. You leave Courmayeur just before midnight on the Monday of HOKA UTMB Mont-Blanc week, cross into France at the Col du Petit-Saint-Bernard and drop to Bourg Saint-Maurice. From there the course loops through the Beaufortain, over the Pas d'Outray, down to Beaufort and back up past Hauteluce. Les Contamines, Col de Tricot and Les Houches bring you into Chamonix. You get 44 hours 55 minutes.

The map shows the 2026 course and its checkpoints. The 2027 course isn't out yet. You have to carry a phone with the LiveTrail app and roaming switched on, and the rules say some areas only let emergency calls through. Download the map before you leave, and GPS will still show where you are when the signal goes.

This is an unofficial guide: Goat Maps isn't affiliated with TDS (Sur les Traces des Ducs de Savoie). Check the official site before you enter or race.

TDS course map

Every course's aid stations on the Goat Maps topo map. Each course has a map of its own further down.

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TDS courses

CourseDistanceClimbingStartTime limit
TDS150.5 km (93.5 mi)9,305 m (30,528 ft)Mon, Aug 24, 11:50 PM44 h 55 min

Start times are the 2026 edition's.

TDS TDS

Courmayeur to Chamonix through the Beaufortain, starting at 23:50 on a Monday with a 44 hour 55 minute limit.

Distance
150.5 km (93.5 mi)
Climbing
9,305 m (30,528 ft)
Start
Mon, Aug 24, 11:50 PM
Time limit
44 h 55 min

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The night section climbs out of Courmayeur past Checrouit and along the Arête du Mont-Favre to Lac Combal. From there it's 19.8 km to the next aid station, over Col Chavannes, the high point of the course, and on to the Col du Petit-Saint-Bernard. You come down through Séez to Bourg Saint-Maurice, the first place your crew can meet you. Then it gets steep: about 1,100 m of climbing in 4.6 km up to Fort de la Platte, which has a cutoff (Tuesday 13:45) and no food, then the Passeur de Pralognan and down to Cormet de Roselend, 15 km after Bourg.

Beyond La Gittaz you climb past Entre deux Nants and over the Pas d'Outray, 18.7 km with nothing in between, to Beaufort at 92 km. That's where your drop bag and a hot meal are. After Hauteluce there are 16.7 km more to Le Signal, past the Girotte dam, then down to Les Contamines. The last long gap, 18.6 km, goes over Col de Tricot to Bellevue, which has a cutoff (Wednesday 18:15) but no services, and down to Les Houches. Checrouit and Séez have drinks only.

The organizer bills the TDS at 145 km and 9,500 m of climbing. The 2026 LiveTrail checkpoints, which this page uses, put the finish at 150.5 km and 9,305 m.

aid stations

kmWhereCutoff
0Courmayeur (start)
7.7Checrouit Maison Vieille (drinks)
16.5Lac Combal Tue 03:30
36.2Col du Petit-Saint-Bernard (Italy to France) Tue 08:30
47.5Séez (drinks)
51.1Bourg Saint-Maurice CrewTue 11:00
66.1Cormet de Roselend Tue 17:15
73.6La Gittaz Tue 19:30
92.3Beaufort Crew, Drop bagWed 03:00
98.6Hauteluce Wed 05:30
115.3Le Signal Wed 11:15
122.8Les Contamines CrewWed 13:15
141.4Les Houches Wed 19:15
150.5Chamonix (finish)
A hiker on a narrow grassy ridge path in the Beaufortain, with rocky peaks behind
Sophie Laurent / Unsplash

Getting an entry

The TDS isn't one of the UTMB World Series Finals, and it has no lottery. For 2026, registration opened at 11:00 CET on January 13 and places went to whoever came first, until the race sold out. What you need is a valid UTMB Index in the 100K or 100M category. Running Stones aren't required, and elite runners get no priority or discount.

You can enter only one race of the week, and you can't sign up for the TDS while you're in the lottery for UTMB, CCC or OCC. In 2026 the fee was €320, plus an 8% administration fee and a carbon contribution that was mandatory. Entries can't be transferred, and you only get your money back with cancellation insurance. Instead of a medical certificate you complete the PPS, a short online health course. Finishing earned 4 Running Stones in 2026, and the UTMB, CCC and OCC lotteries need at least one.

Getting to the start in Courmayeur

A road up to a chalet-style building in Courmayeur, with jagged snowy peaks behind
Angelo Casto / Unsplash

The race runs buses to the start from Chamonix and other towns in the valley. Your seat is free, but you have to book it in MyUTMB, and in 2026 the booking window closed on July 12. On race day the buses left Chamonix every half hour from 17:00 to 21:00 and took an hour to reach Courmayeur. After the race, Arriva's bus takes you from Chamonix back to Courmayeur if you show your bib.

Geneva is the nearest airport, about 115 km from Courmayeur, and a Flixbus runs from Geneva to Courmayeur. Turin Caselle is about 150 km away and Milan Malpensa about 212 km. The organizer says not to rent a car: the car parks in Courmayeur fill up during race week.

Crewing and drop bags

The lake below the Cormet de Roselend, under green mountains, with pines, a chalet and a track on the meadow above the water
Thomas MARCHAND / Unsplash

Your crew can meet you at three aid stations: Bourg Saint-Maurice, Beaufort and Les Contamines. Only one person can help you, in the area set aside for it, and they can hand you a bag of 30 liters at most. Beyond that they may give you a massage or see to a blister while you sit on a chair, and nothing more medical. Crewing anywhere else costs an hour. There are no pacers: being accompanied outside the spectator zones near aid stations costs 15 minutes each time.

The organizer strongly recommends that supporters use its coaches rather than drive. In 2026 the TDS pass cost €62 for one adult, on sale from June 9 to July 12, and every seat had to be booked. The coaches ran to the Col du Petit-Saint-Bernard, Bourg Saint-Maurice, Cormet de Roselend, Beaufort and Les Contamines, and from Beaufort back to Chamonix through Hauteluce.

You get one 30 liter drop bag at race-pack pick-up, and on the TDS it waits at Beaufort. Don't put poles in it.

Weather and what to carry

A rock pinnacle and scree slopes in the Beaufortain, half hidden by cloud
Wild_er / Unsplash

August in Bourg Saint-Maurice averages a high of 26.4°C and a low of 12.6°C (Météo-France, 1991 to 2020), but much of the course runs far higher. The organizer warns that it can be over 30°C, or down to -10°C above 2,000 m, with rain, hail or snow, and that your kit has to see you through one or two nights out.

The TDS kit list includes two headlamps, each with backup power, a hooded waterproof jacket, waterproof overpants, a warm second layer, a beanie, warm waterproof gloves, a survival blanket, a whistle, at least 1 liter of water (1.5 is recommended) and a 15 cl cup, since aid stations hand out no disposable cups. If you start with poles, you carry them all the way to Chamonix.

TDS aid stations and GPS coordinates

For crews and spectators: each place on the map in decimal degrees, latitude first. Paste them into any map app or add them as waypoints in Goat Maps.

  • Courmayeur (start)

    1,222 m (4,009 ft)

    45.79288, 6.97158

  • Checrouit Maison Vieille (drinks)

    1,956 m (6,417 ft)

    45.79064, 6.93127

  • Lac Combal

    1,971 m (6,467 ft)

    45.76921, 6.85153

  • Col Chavannes

    2,574 m (8,445 ft)

    45.74952, 6.83495

  • Col du Petit-Saint-Bernard (Italy to France)

    2,183 m (7,162 ft)

    45.68328, 6.88580

  • Séez (drinks)

    904 m (2,966 ft)

    45.62328, 6.80102

  • Bourg Saint-Maurice

    838 m (2,749 ft)

    45.61721, 6.76626

  • Passeur de Pralognan

    2,554 m (8,379 ft)

    45.66871, 6.71218

  • Cormet de Roselend

    1,969 m (6,460 ft)

    45.69122, 6.69012

  • La Gittaz

    1,657 m (5,436 ft)

    45.72276, 6.67436

  • Pas d'Outray

    2,167 m (7,110 ft)

    45.72631, 6.61774

  • Beaufort

    740 m (2,428 ft)

    45.71579, 6.57169

  • Hauteluce

    1,178 m (3,865 ft)

    45.74995, 6.58099

  • Le Signal

    1,875 m (6,152 ft)

    45.78659, 6.69352

  • Les Contamines

    1,152 m (3,780 ft)

    45.82218, 6.72624

  • Col de Tricot

    2,117 m (6,946 ft)

    45.85040, 6.76997

  • Les Houches

    1,009 m (3,310 ft)

    45.88999, 6.79813

  • Chamonix (finish)

    1,035 m (3,396 ft)

    45.92364, 6.86930

TDS FAQ

When is the TDS 2027?

The 2027 dates hadn't been announced when this page was checked. The 2026 TDS started at 23:50 on Monday, August 24, and its time limit ran to 20:45 on Wednesday the 26th, at the start of a race week that ended on August 30.

Do you need Running Stones for the TDS?

No. In 2026 the only condition was a valid UTMB Index in the 100K or 100M category, and entries went first come, first served. Finishing the TDS earned 4 Running Stones.

How long is the TDS and how much climbing is there?

The organizer gives 145 km and 9,500 m. The 2026 checkpoints put the finish at 150.5 km and 9,305 m. The limit is 44 hours 55 minutes. In 2026, 715 of the 1,290 starters finished, and Rémy Brassac and Sarah Vieuille won.

What does TDS stand for?

Sur les Traces des Ducs de Savoie, which means on the trail of the Dukes of Savoy. The race links the Aosta Valley in Italy to the Savoie in France.

Can you have a pacer or crew on the TDS?

No pacers. One crew member can meet you at Bourg Saint-Maurice, Beaufort and Les Contamines. Being accompanied outside the spectator zones costs 15 minutes each time.

Is there cell service on the TDS course?

You must carry a smartphone with the LiveTrail app and roaming on, and keep it switched on: airplane mode costs 15 minutes. The rules warn that in some areas only emergency calls go through.

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Updated . An unofficial guide, from the organizer's published information. Coordinates from the organizer's course and OpenStreetMap contributors. Photos from Unsplash. Organize a race? We help with course files.