Preparation guide · La Marmotte Granfondo Alpes
La Marmotte 2027: how to prepare it and what to eat on each climb
The next edition is on Sunday 27 June 2027 (provisional date: tourism listings show it as «to be confirmed»; in 2026 it was held on 28 June. Start time is indicative), starting in Bourg d'Oisans (Alps, France) at 7:00. Here you have the route of La Marmotte, its climbs, the usual weather and how much to eat and drink for your target time.
La Marmotte: route and profile
Official 2025 route (organisers' GPX).
| Climb | Where | Length | Gain | Average grade | Top |
|---|---|---|---|---|---|
| Climb at km 6 | km 6–22 | 15.6 km | +576 m | 3.7 % | 1,287 m |
| Climb at km 23 | km 23–32 | 8.9 km | +593 m | 6.7 % | 1,790 m |
| Col du Glandon | km 34–37 | 2.7 km | +184 m | 6.8 % | 1,914 m |
| Col du Télégraphe | km 60–93 | 32.2 km | +1102 m | 3.4 % | 1,574 m |
| Col du Galibier | km 97–116 | 18.8 km | +1137 m | 6.1 % | 2,546 m |
| Alpe d'Huez | km 162–176 | 13.8 km | +1093 m | 7.9 % | 1,811 m |
The climbs and key sections, one by one
| Climb or section | Length | What it's like and how to ride it |
|---|---|---|
| 1. Bourg d'Oisans → foot of the Glandon km 0 | 6.3 km | Flat along the Romanche valley: start in pens, very fast and crowded. Sit in, with no surges or scares. Don't try to move up: there are over 5,000 m to go. |
| 2. Glandon I: Allemond and the dam km 6.3 | 15.6 km avg 3.7 % · max 15.2 % | Starts gently along the valley and steepens on the ramps by the Allemond dam (very short pitches over 12 %). It's the first climb and everyone goes up too fast: you, at 70–75 % of FTP. On the ramps, an easy gear and seated. |
| 3. Glandon II: up to Grand Maison km 23.4 | 8.9 km avg 6.7 % · max 10.9 % | After a short descent, the real climb: 9 km at 6.7 % up to the Grand Maison dam area. Steady pace and eat something every 20 minutes: the first station with food is at the top (km 36). |
| 4. Glandon III: final ramp to the col km 33.9 | 2.7 km avg 6.8 % · max 9.2 % | Final kick to the Col du Glandon (1,924 m), with the hardest kilometre at the end. Stop at the station (km 36): fill bottles, eat solid food and cover up for the descent. |
| 5. Glandon descent km 36.6 | 23.4 km | 23 km descent to the Maurienne, narrow with tight bends at first. The organisers usually neutralise it (it isn't timed): check the rules. No risks: if it's neutralised there's nothing to gain. Brake before the bends and leave space. |
| 6. Maurienne valley km 60 | 20.5 km avg 1.3 % · max 5.9 % | 20 km of uphill false flat along the valley, often into a headwind. The most important stretch for saving energy: get on a group, eat solid food and drink. Those who ride it alone pay for it on the Galibier. |
| 7. Col du Télégraphe km 80.5 | 12.1 km avg 6.9 % · max 10.3 % | Steady climb through woodland from Saint-Michel-de-Maurienne up to 1,566 m, with shade. At 70–75 % of FTP, chasing nobody: what comes next is higher and longer. Drink at the water stations (km 79 and 92). |
| 8. Descent to Valloire km 92.6 | 4.3 km | Short descent to Valloire, with the food station at km 98. Stop and eat well in Valloire: it's the last real food before the Galibier. |
| 9. Galibier I: Valloire → Plan Lachat km 96.9 | 11.1 km avg 6 % · max 9 % | First half open and steady along the Valloirette valley. Don't be fooled: it looks easy, but the highest part is still to come. Hold the same power as on the Télégraphe. |
| 10. Galibier II: Plan Lachat → summit km 108 | 7.7 km avg 6.2 % · max 10.4 % | After the Plan Lachat bend it steepens through hairpins to over 2,500 m: thinner air, cold and sometimes snow by the roadside. Altitude takes power away: drop your watts by 5 % and don't worry if your heart rate won't rise. Food station at the top (km 115): cover up before the descent. |
| 11. Lautaret descent to Bourg d'Oisans km 115.7 | 46.4 km | 46 km almost all downhill via the Lautaret and La Grave, with tunnels (some dark) by the Chambon lake and a few rises. Ride in a group and eat and drink now: it's your last chance before the Alpe. Rear light or clear lenses for the tunnels. Stop in Bourg d'Oisans (km 162). |
| 12. Alpe d'Huez km 162.1 | 13.8 km avg 7.9 % · max 11.8 % | The 21 hairpins: hardest in the first ones (21 to 16, over 10 %), a bit easier through Huez and at the end. In early afternoon heat with little shade. Set off with both bottles full and climb with whatever is left, ignoring this morning's power: 65–75 % of FTP with 150 km in your legs is already a lot. Water on your neck at the stations (km 165 and 170). |
Route keys
- About 175 km and over 5,000 m with four climbs: Glandon, Télégraphe, Galibier and Alpe d'Huez. The key is to reach the Alpe with something left: the first three are climbed at 70–75 % of FTP, even if people pass you.
- Five of the nine stops are water only (km 79, 92, 107, 165 and 170). Real food is at km 36 (Glandon), 98 (Valloire), 115 (Galibier) and 162 (Bourg d'Oisans): eat plenty there and carry gels or bars for the rest.
- The Maurienne valley (km 60–80) and the Lautaret descent (km 116–162) are ridden in a group: 65 km where the day is saved or wasted. Eat solid food on them.
- The Galibier goes above 2,500 m: up there your power drops (altitude takes away 5–8 %), it's cold and can be windy even if it's 25 ºC below. Gilet and arm warmers for the descent.
5 more keys in WinWatts: with the forecast for the days before, the wind and heat section by section, and on which climbs to eat and drink.
La Marmotte: what to eat and drink
How much a typical rider (72 kg) needs depending on their time. From 2–3 hours on, what matters most is eating carbs regularly (every 20–30 minutes) and drinking before you're thirsty.
| Total time | Carbs per hour | Total carbs | Drink per hour | Total drink | Sodium per hour |
|---|---|---|---|---|---|
| 7 h | 75 g/h | 445 g | 650 ml/h | 4.5 l | 450 mg/h |
| 8 h | 75 g/h | 515 g | 550 ml/h | 4.4 l | 450 mg/h |
| 9 h | 75 g/h | 590 g | 650 ml/h | 5.9 l | 450 mg/h |
| 10 h | 75 g/h | 650 g | 650 ml/h | 6.5 l | 450 mg/h |
More than 60–90 g of carbs per hour only if you've trained it. Don't try on race day what you haven't tolerated in training.
Section by section between feed stations (for about 8 h)
At the feed stations (km 36, 79, 92, 98, 107, 115, 162, 165, 170) you stop, eat something and refill your bottles (the ones at km 79 and 92 and 107 and 165 and 170 only have drinks). But what matters most is what you take on the move until the next one: this table tells you how much. You can pick it up at the station or carry your own gels and bars; what matters is spreading it out, not eating it all at once when you stop.
| Section | Duration | Carbs to take in the section | Drink in the section |
|---|---|---|---|
| km 0 → 36 | 1 h 55 | 145 g | 1,050 ml |
| km 36 → 79 | 1 h 10 | 85 g | 650 ml |
| km 79 → 92 | 1 h | 75 g | 550 ml |
| km 92 → 98 | 0 h 10 | 15 g | 100 ml |
| km 98 → 107 | 0 h 37 | 45 g | 350 ml |
| km 107 → 115 | 0 h 38 | 45 g | 350 ml |
| km 115 → 162 | 1 h 18 | 100 g | 700 ml |
| km 162 → 165 | 0 h 16 | 20 g | 150 ml |
| km 165 → 170 | 0 h 27 | 35 g | 250 ml |
| km 170 → 176 | 0 h 29 | 35 g | 250 ml |
The key section is the first one: there's no feed station until km 36, so you leave Bourg d'Oisans with full bottles and about 145 g of carbs on you (for example, 3 gels and a bar).
Not going to take 8 h? In WinWatts you set your target time and the feed stations, and you see these sections with your real pace on each climb. You can also compare scenarios: what changes if you go faster or slower.
La Marmotte: weather in late June
What the weather was like on the last Sunday of June in recent editions (in Bourg d'Oisans, not on the passes):
| Year | Low | High | Rain | Max wind |
|---|---|---|---|---|
| 2022 | 12 ºC | 25 ºC | 0.3 mm | 13 km/h |
| 2023 | 15 ºC | 26 ºC | 0.0 mm | 11 km/h |
| 2024 | 12 ºC | 22 ºC | 4.8 mm | 10 km/h |
| 2025 | 17 ºC | 32 ºC | 2.1 mm | 8 km/h |
| 2026 | 17 ºC | 32 ºC | 0.0 mm | 11 km/h |
Your La Marmotte, tailored to you
This guide uses a typical rider. In WinWatts we calculate it with your data:
- Your time, average power and finish time from your FTP and weight.
- The race-day forecast for each section, and what to wear.
- Your food and drink plan kilometre by kilometre, with your gels, bars and bottles.
- Your training plan until Sunday 27 June 2027, adjusted every week to how you're doing.
WinWatts is not affiliated with the organisers of the La Marmotte. Dates, routes, schedules and registration: official website. Route measured on the official 2025 GPX; feed stations published by the organisers (check against the 2027 edition); weather from past editions (Open-Meteo). For guidance only: it doesn't replace advice from a health professional.