The Bison Trail is a backyard-style trail race in Besançon, Doubs, eastern France, held at the Complexe sportif Michel Vautrot la Malcombe. Runners complete a short, steep loop of approximately 6 km, with sources indicating about 250 to 300 metres of climbing per loop. The race is offered in 36 km or 72 km distances. Participants have one hour to finish the loop and refuel before the next hourly start, challenging their pacing, climbing ability, and recovery speed.
Unlike a traditional last-runner-standing Backyard Ultra, Bison Trail uses a shorter loop and set distance goals: six loops for the 36 km race or twelve for the 72 km option. It is open to solo runners and teams, including relay groups and individuals aiming to finish the full distance. The event has attracted around 400 runners per edition, with some participants coming from outside France. A race village, fair-style activities, and entertainment are available near the Malcombe site. Its connection to Laz, a figure linked to the Barkley Marathons and Backyard Ultra culture in the United States, lends the format a distinct ultrarunning character, despite the Besançon version being shorter and more structured.