Grand Colombier from Culoz: two steep halves and one breather

The Grand Colombier is the big mountain of the Bugey, in the Ain, and its pass is 1,501 m high. From Culoz it is 18.3 km and 1,262 m of climbing, by the Bugey Sud tourist office's figures, with pitches at 14%. Since 2012 it has gone from an unknown local climb to a regular on the Tour de France. It is not one steady climb but two steep ones split by a short easy stretch, with heat at the bottom and steep ramps near the top. Here is how it is built, how to ride it, and the car-free days that make it the best climb in the region to ride on a Saturday.

The climb from Culoz

Ain Tourisme gives the climb as 17.6 km from Culoz at 244 m, which is exactly the length of our track; the Bugey Sud tourist office measures 18.3 km. The difference is where in Culoz you start.

• Culoz to the Anglefort junction: the hot part. The road climbs out of Culoz in a series of bends, steep throughout, with a pitch at 14%. The tourist office warns that the first 7 km are very hot, between vineyards and cliffs. On our track the first 6 km never drop below 7.2%, and the sixth averages 11.1%.
• The breather. At 878 m the road joins the road from Anglefort, and the next 2 km or so run at about 3%. This is the only easy part of the climb. Drink and eat here.
• Through the forest. After the junction the road steepens again, and Ain Tourisme describes very difficult sections with the forest as the only relief. Our track has 9–10% for two kilometres here, the hardest part of the second half.
• From La Sapette to the top. Above La Sapette, at 1,230 m, Ain Tourisme describes the last section as generally less difficult. But the tourist office's advice is to keep some strength for the end, and our track shows why: its last half-kilometre averages more than 10%.

How to ride it

Ain Tourisme gives about two and a quarter hours; fit riders will be quicker. Either way that makes it a long tempo or sweet-spot effort, not a threshold one.

• Go early. The first 7 km are exposed and the tourist office calls them very hot. Start before the sun is high in summer, and read hydration in the heat if you can't.
• Hold back on the first ramp. Six kilometres at 7–11% straight from the valley tempts you to ride too hard too soon. Stay at 80–85% of FTP; our guide to pacing a climb with power explains why.
• Use the breather to recover, not to go faster. The 3% stretch after the junction is where you eat and lower your heart rate, because what follows is steep again.
• Gear low. With pitches at 14%, a compact and a 32 or 34 sprocket are not too much. See gearing for climbing.

From unknown to a Tour regular

Ain Tourisme says the climb from Culoz was discovered during the tenth stage of the 2012 Tour de France, when Thomas Voeckler was first over the top. Since then the Tour has come back again and again. The Bugey Sud tourist office lists 2012, 2016, 2017, 2020 and 2023, and a stage finish is planned for Sunday 11 July 2027.

Locally, the climb has its own brotherhood. The Fêlés du Grand Colombier is a club for riders who take on several ascents of the mountain, including up-and-down rides from different sides on the same day.

When to go, and the car-free days

• Season. The tourist office says the roads over the Grand Colombier are generally closed from November to the second half of April. In 2026 the road from Culoz was closed for part of the summer for safety work and reopened on 3 September. Check with the tourist office before you go.
• Journées cyclo. On four Saturdays a year the roads are reserved for cyclists from 7:00 to 15:00. In 2026 they were 20 June, 11 July, 8 August and 12 September. They are free, there is no registration, and the tourist office offers coffee at the Maison du Vélo in Culoz.
• The other sides. From Anglefort it is 15.7 km and 1,251 m. From Artemare via Virieu-le-Petit it is 15.9 km and 1,251 m, with a passage at 22%. From Champagne-en-Valromey via Lochieu it is 12.3 km and 900 m, the easiest side. To descend, Lochieu is the gentler choice.
• At the top. From the parking at the col it is about a 20-minute return walk to the orientation table below the Croix du Grand Colombier. Ain Tourisme describes the view as taking in the Alps, Mont Blanc, the Rhône, and the lakes of Bourget, Annecy and Geneva.

Ride it in Moveee Indoor

The route on this page is the real road from Culoz to the col. In Moveee Indoor your smart trainer reproduces its gradient, from the steep bends above Culoz to the 3% breather and the forest after it, and the world around you is built from map data of the place. What it teaches you indoors is how to use the one easy section: ride it once at a steady effort, then again with a slightly harder first half, and see which gives the better time to the top.

Your rides are saved with power data, so the comparison is easy. If you prefer to use another device, download the GPX above.

The short version

18.3 km and 1,262 m from Culoz to 1,501 m, by the tourist office's numbers, with pitches at 14%. It is steep at the bottom, easy for 2 km in the middle, then steep again through the forest. Go early to avoid the heat, recover in the middle, and plan your trip around one of the Saturday car-free days if you can.