Thonon-les-Bains sits on the southern shore of Lake Geneva, facing Switzerland across about ten kilometres of water, and it is where the Route des Grandes Alpes officially starts. This was the first great tourist road of France, planned in the early twentieth century by the Touring Club de France to link the lake with the Mediterranean via the highest passes of the French Alps, and the road runs for about seven hundred kilometres over a series of cols, ending in Menton. The fine promenade along the lake, with its views of the Swiss shore and the Jura, and the fish restaurants serving perch fillets, are a gentle prelude.
The old town stands on a bluff above the port, linked to the lakeside by a funicular opened in the late nineteenth century, and nearby the Château de Ripaille, a former residence of the dukes of Savoy, stands in a park beside the water. Thonon was a spa town, and the neighbouring Évian, a few kilometres east, still sells its mineral water around the world. This region, Savoy, belonged to the House of Savoy until it was ceded to France in 1860, and its mountain culture, cheeses and dialect set it a little apart.
The ride proper begins when the road turns south and climbs into the Alps. The first passes are modest, in forests and pastures with Alpine chalets and cow bells, but the route builds toward the giants: the Col de l'Iseran, at 2,764 metres the highest pass in the Alps that is crossed by a through road, the Col du Galibier, at about 2,640 metres, and finally the Col de la Bonette, near 2,715 metres. The road surface is generally good, but bends are tight, there are drops without guard rails in places, and the weather at altitude can switch from sun to snow in minutes. The high passes are only open in summer, typically from June until October, so check status before planning. Early starts avoid the afternoon storms.
At the beginning, everything is easy. Thonon is a town of over thirty thousand, with fuel stations on the main roads and plenty of cafes, hotels and supermarkets, so fill up and eat well. Higher up, villages are small and stations rarer, so top up whenever you pass one. Alpine cheeses, such as reblochon and beaufort, and a savoyard dish of potatoes baked with cheese and bacon, called tartiflette, are the natural fuel for the road. Pack warm layers, rain gear and gloves, whatever the weather at the lake.