QBRC, which stands for Quelques bonnes raisons de courir, is a trail race held in Viroflay, located in the Yvelines department west of Paris. It typically takes place in late August or early September. The race focuses on forest trails rather than roads, offering two primary distances: 12 km and 20 km. The event was established in 2010 by the QBRC association and is currently organized by Viroflay Running Trail.
The courses traverse the Fausses Reposes forest, with approximately 90% of the race on woodland terrain. The 12 km route includes about 250 meters of elevation gain, and the 20 km route has around 450 meters. The course layouts are frequently altered between editions. The most recent edition saw participation from about 320 runners, with the 12 km distance being the preferred choice. QBRC maintains certain traditions, including a solidarity project, organic food and beverages at aid stations, and a relaxed local atmosphere distinct from a large urban race.