Defi de Fort l'Écluse 2026

The Defi de Fort l'Écluse is a trail race starting in Léaz, a village in Ain near the Haut-Jura natural park, offering 12 km and 19 km routes. Held in mid-October, it combines road sections, paths, wide tracks, and narrow single track. The 19 km route presents a significant climbing challenge, featuring approximately 950 meters of elevation gain. The course runs near the Vierge de Léaz, a designated site overlooking the Rhône and the Fort l'Écluse gorge. A notable part of the route goes through the fort itself, via an underground gallery containing 917 stairs. This stair passage distinguishes the race, giving it the character of a demanding run through mountain history rather than a typical local trail event.