La Sans Raison 2026

La Sans Raison is a mid-November trail-running event held in Vélizy-Villacoublay, in the Yvelines department west of Paris. It features three main distances: 11 km, 23 km, and 42 km, along with races for children and juniors. The event supports the Laurette Fugain Association in its fight against leukemia. The three adult races are named the 11 km La LaiseTrail, the 23 km La ThérèseTrail, and the 42 km La BalèzeTrail. The routes are single-loop trail courses incorporating town and stadium settings, indicating it is a local trail event within the community of Vélizy-Villacoublay, not a remote mountain race. The combination of full-distance runners, shorter-distance participants, younger runners, and charity supporters creates a broad, family-friendly atmosphere while maintaining the challenge of the longer trail options.