Les 24 Tours Sans Venin is a looped elimination trail race at the foot of the Vercors, near Grenoble in Auvergne-Rhône-Alpes. Runners navigate the same 6 km circuit repeatedly, with approximately 280 m of elevation gain per loop and no road crossings. The objective is straightforward: complete the loop within an hour, rejoin the start line on the next hour, and continue until your selected duration concludes or you miss the time limit. Available options include 4-hour, 7-hour, and 24-hour races, allowing the event to function as a demanding short trail challenge or a complete Last Man Standing-style endurance test.
The maximum distance in the longest version reaches 144 km with around 6,720 m of total elevation change, including 23 aid stations throughout the entire race. The 24-hour race is designed for participants aiming to measure their performance loop by loop against the consistent climb, the identical descent, and the constraint of the hourly restart. Courir à Seyssins-Seyssinet is the organizing body, and the event's structure permits spectators, including friends and family, to observe runners multiple times, offering more visibility than just at the start and finish. The concept draws inspiration from Lazarus Lake’s Barkley Marathons, yet the execution is local, contained, and clear: one loop, one hour, then repeat.