Trail du Grand Colombier

The Trail du Grand Colombier is a monumental 55-kilometer race with 3,400 meters of elevation gain, starting from Culoz in the Ain department. The Grand Colombier, the highest point of the Bugey at 1,534 meters, is a giant of the southern Jura whose formidable slopes are well known to cyclists — the Tour de France has written some of its most heroic pages here. For trail runners, this mountain represents a sizeable challenge with an elevation-to-distance ratio among the highest of any trail race in France.

The course is a spectacular succession of ascents and descents around the Grand Colombier and surrounding peaks. Runners climb the mountain's flanks from different faces, discovering the diversity of its landscapes. The western slope, above Lake Nantua, is covered with dense beech and fir forests. The eastern slope, overlooking the Rhône and Lac du Bourget, offers vertiginous limestone cliffs and exceptional Alpine panoramas. The summit ridges, vast alpine pastures scattered with karst dolines, recall the high Jurassian plateaus with their gentians and narcissus in spring.

The 3,400 meters of elevation gain are brutally demanding. The climbs are long, steep, and unforgiving, with passages exceeding 35% gradient. Each descent is followed by an equally demanding climb, with never a recovery plateau. The karst terrain is technical: sharp lapiaz that cut into shoe soles, dolines where footing gives way, forest trails carved into deep ruts by runoff, and polished, slippery limestone slabs. Weather can be capricious with sudden fog on the ridges, violent wind, and summer storms that transform trails into torrents.

Culoz is a small town in the Ain department nestled at the foot of the Grand Colombier, on the right bank of the Rhône, facing the Chartreuse massif and Lac du Bourget. Culoz station, on the Lyon-Geneva line, makes it a practical access point. The town is dominated by the Château de Culoz, a 13th-century fortress perched on a rocky spur. The Lavours marshes, a national nature reserve nearby, constitute one of the last alkaline peat bogs in France, a rare ecosystem populated by dragonflies, herons, and beavers.

For international runners, the Trail du Grand Colombier is a major challenge that rivals Alpine ultras in terms of physical demand. Located between Lyon and Geneva, accessible by train or plane, this trail offers the opportunity to take on one of the most feared summits in world cycling in a trail format. The wild beauty of the southern Jura, combined with the gastronomy of the Ain department — Bresse poultry, Comté cheese, Bugey wine — and the proximity of Lac du Bourget and Aix-les-Bains, makes this race a complete sporting event in an exceptional natural setting.