Col du Glandon is a high mountain pass at an elevation of 1.930m (6,332ft) above the sea level, located in the Savoie department in the Auvergne-Rhône-Alpes region in south-eastern France. It’s one of the toughest climbs in the French Alps.
The road to the summit is nestled on the border between Isère and Savoie, within the Dauphiné Alps. It’s totally paved. The pass is 46.4 km (28.83 miles) long, running from Barrage du Verney to La Chambre. This is the first climb and descent that is used in La Marmotte sportive every July.
The pass is usually closed from the beginning of November to mid May. The road to the top is a varied climb with a range of slopes, with great views at the summit. The road opened in 1898 and was first used in the Tour de France in 1947. Since then it has been used many times.
The road to the summit is steep, hitting a maximum gradient of 15.5% through some of the ramps. It gets a decent amount of traffic in summer. The col de Glandon is a straightforward col with a gradient that increases near the summit with the last seven kilometres being the toughest on the whole climb. The last two kilometres are over ten percent with stretches of 12 percent. There are 2 routes to reach the summit. Starting from Barrage du Verney, the ascent is 24.12 km long. Over this distance, the elevation gain is 1.152 meters. The average percentage is 4.8 %. And starting from La Chambre, the ascent is 21.3 km long. Over this distance, the elevation gain is 1.472 meters. The average percentage is 6.9 %.