The Route des Grandes Alpes is the classic French Alpine crossing: roughly 720 km (447 miles) from Thonon-les-Bains on Lake Geneva to Menton on the Mediterranean, linking the highest paved passes inside France into one continuous itinerary. Construction started in 1909, the route opened in 1913, it was fully paved in 1937, and it took the name Route des Grandes Alpes in 1950. On a motorcycle it is a four-to-six day ride rather than a day trip, and the thing that decides whether the trip works is not fitness or bike choice — it is whether the high cols are open. The whole line is reliably passable only between roughly June and October, and the very highest passes clear later than the rest.
What the route actually is
It helps to understand that the Route des Grandes Alpes is a signed tourist itinerary, not a single numbered road. It stitches together departmental roads — long stretches of the D902 and D1091 among them — and it exists because someone in 1909 decided the French Alps needed a north-to-south touring line at a time when the region was still awkward to reach. That origin explains the character. The road was laid out to visit passes, not to avoid them, so the profile is relentlessly up-and-down: you rarely spend an hour without climbing or descending something.
The itinerary runs from Thonon-les-Bains via Les Gets and Cluses, then Saint-Gervais and Megève over the Col des Saisies, on through Beaufort and Bourg-Saint-Maurice to Val-d'Isère and the Col de l'Iseran. From there it drops to Modane, climbs the Col du Galibier, crosses the Col du Lautaret to La Grave, heads for Briançon and the Col d'Izoard, then Embrun, the Col de Vars, and Barcelonnette via Jausiers. At Jausiers you choose: south over the Col de la Bonette, or the alternative line over the Col de la Cayolle. The southern end continues through the Alpes-Maritimes over cols including Saint-Martin, Turini and Castillon before dropping to the coast. Motorised traffic traditionally finishes at Menton; the modern cycling version was rerouted to Nice in 2012, adding about 37 km and the Col d'Èze.
Route at a glance
| Length | About 720 km (447 miles), Thonon-les-Bains to Menton |
| Highest point | Col de l'Iseran, 2,764 m (9,068 ft) |
| Other high cols | Galibier 2,642 m, Izoard 2,360 m, Vars 2,111 m, Lautaret 2,058 m |
| Optional high loop | Cime de la Bonette, 2,802 m (9,193 ft) |
| Opened | 1913; fully paved 1937; renamed 1950 |
| Realistic riding time | 4–6 days at touring pace |
| Full-route season | Roughly June to October (verify before departure) |
Open the Thonon to Menton line in Google Maps — a straight routing will try to send you down the motorway, so treat it as a frame and drop in the cols as waypoints before you send it to your navigation.
The northern third, Lake Geneva into the Tarentaise
The first day out of Thonon-les-Bains is the gentlest riding on the whole route and the part people are most tempted to rush. Don't. The Chablais and Aravis section rolls over medium cols — Col des Gets at 1,163 m, Col de la Colombière at 1,613 m, Col des Aravis at 1,487 m, Col des Saisies at around 1,633 m — through pasture, cowbells and ski villages that look completely different in August than they do in their winter marketing photos. The Cormet de Roselend at 1,967 m is the first stretch that feels genuinely high, with a reservoir and a long open descent to Bourg-Saint-Maurice.
Because these northern cols sit lower, they open earlier in the year. If you are riding in late May or early June, this is the section that will be rideable while the passes further south are still gated.
The high middle, Iseran to Izoard
This is why people ride the route. From Bourg-Saint-Maurice the road climbs to Val-d'Isère and then to the Col de l'Iseran on the D902 — at 2,764 m the highest paved pass in the Alps, connecting the Isère valley (the Tarentaise) with the Arc valley (the Maurienne), between Val-d'Isère in the north and Bonneval-sur-Arc in the south. The pass is only accessible by road in the summer months. The summit is a bare saddle with a chapel and a car park, and the descent to Bonneval-sur-Arc is one of the great alpine downhills.
Next comes the Col du Galibier at 2,642 m, reached from the Maurienne side over the Col du Télégraphe and Valloire. The north climb from Valloire is 18.1 km at an average of 6.9%, gaining 1,245 m. Below the summit sits a 370 m tunnel that reopened in 2002 after restoration; the road over the top is the better ride. South of the Galibier the road drops to the Col du Lautaret at 2,058 m, which is a different animal — a wide, open, year-round pass on the D1091 between Grenoble and Briançon, linking the Romanche and Guisane valleys.
From Briançon the D902 climbs the Col d'Izoard at 2,360 m, generally open from late May to late October, with the lunar rock field of the Casse Déserte on its southern side. Then Vars at 2,111 m and the descent to Barcelonnette. If you have the time and the weather, take the Bonette detour from Jausiers — the loop road around the Cime de la Bonette tops out at 2,802 m, higher than anything else on the itinerary.
The southern third, Alpes-Maritimes to the sea
South of Barcelonnette the character changes again. The Cayolle line at 2,327 m and the string of Alpes-Maritimes cols — Valberg 1,673 m, la Couillole 1,678 m, Saint-Martin 1,500 m, Turini 1,607 m, Castillon 728 m — trade glaciers for limestone, pine and gorges. The Col de Turini is the one most riders recognise from rally footage, and it rides tighter and more technical than anything in the north.
The last hour into Menton is a jarring transition: 2,000 m of altitude gone, temperature up ten degrees or more, and Riviera traffic where you had empty hairpins. Plan the final day short. Arriving hot, tired and dehydrated into coastal traffic is where the trip most often goes wrong.
Season, tolls and practical detail
Season. The route is fully open roughly between June and October. Most passes are open by the end of May, but the highest — Iseran, Galibier, Izoard — are typically clear only after mid-June at the earliest, and the high cols close when the first snow arrives, which can be October or earlier. As of August 2026 that pattern holds, but it is weather-driven every single year, so check the official status before you commit to a day's route: the Hautes-Alpes and Savoie departments publish live col status, and the tourist offices in Valloire, Briançon and Barcelonnette will tell you what is actually open.
Tolls and restrictions. France has no national motorway vignette; the autoroutes are tolled per journey, and the Route des Grandes Alpes itself avoids them almost entirely. Several French cities operate low-emission zones (ZFE) requiring a Crit'Air sticker — that matters if you route through Grenoble, Lyon or Nice, not on the cols themselves. Check the current rules on the official Crit'Air site before you cross a city, and note that requirements change from year to year.
Fuel. Stations exist in the valley towns, not on the passes. Bourg-Saint-Maurice, Modane, Briançon, Barcelonnette and Saint-Étienne-de-Tinée are the reliable anchors. Filling up in the valley before every big climb is the simple rule, because a 25 km climb, a 25 km descent and a headwind eat more range than the map suggests.
Weather. Afternoon thunderstorms are routine over the high cols in July and August, and a summit at 2,700 m can be 15 °C colder than the valley you left an hour earlier. Riders report starting in shirtsleeves at Bourg-Saint-Maurice and needing full layers at the Iseran on the same morning. Hail on descents is not rare.
Gear notes for a multi-day alpine crossing
Two things separate a smooth run from a frustrating one here. The first is navigation that does not depend on signal. Large parts of the high valleys have patchy mobile coverage, and the signed itinerary is easy to lose where it leaves a village. Downloading the whole corridor for offline navigation on a handlebar display before you leave Thonon means the route survives the dead zones, and planning the days in advance with a proper route planning workflow keeps the col-by-col waypoints in one file instead of on a napkin. Riders on the JADO S6 get that map on a screen that stays readable in alpine glare, with the phone shut away from the hail.
The second is tyres. Six days of 1,500 m climbs and descents put your tyres through more temperature and pressure swing than most road riding ever does, and the effect is largest exactly where you least want vague handling. Our tire pressure guide covers what altitude and heat cycling do to a set of pressures, and a TPMS sensor puts the number on the screen instead of leaving you to guess at a col-top car park. On a route where you may be four hours from a garage, a slow puncture you spot early is a stop, not a recovery truck.
Worth adding for a trip this long: charging. Mountain refuges and small hotels rarely have enough sockets, and a bi-directional 100 W charger that fills the phone off the bike during the day and works as a power bank in the evening removes one recurring annoyance.
If you want the individual passes in detail, we cover the Galibier and Lautaret pairing, the Bonette high loop and the Izoard and its Casse Déserte separately.
FAQ
How many days do you need for the Route des Grandes Alpes?
Four to six days is realistic on a motorcycle. Three is possible but turns the high passes into transit. Six lets you absorb a weather day, which the Alps will eventually hand you.
When is the route fully open?
Roughly June to October. Most passes open by late May, but the Iseran, Galibier and Izoard usually clear only after mid-June, and closure comes with the first significant snow. Verify with departmental road information before departure — these dates move every year.
Which direction should you ride it?
North to south, Thonon to Menton, is the traditional direction and gives you the sea as a finish. South to north works equally well mechanically; the argument for it is that you get the hardest, highest riding on days three and four when you have adapted to the roads.
Is a big touring bike suitable?
Yes. The passes on the main itinerary are properly surfaced two-lane roads, not gravel tracks. The limiting factors are hairpin radius on a heavily loaded bike and brake heat on long descents, not road quality.
Are there tolls on the route?
The cols themselves are free. French motorways are tolled per journey, and some cities require a Crit'Air low-emission sticker, so check the official rules if you plan to route through a large city rather than around it.
