Bike Marathon Lumnezia is a demanding cross-country mountain bike marathon held in the Lumnezia valley of the canton of Graubunden, Switzerland. A smaller, community-rooted event by Swiss standards, it draws a modest but committed local field and carries the unpretentious atmosphere typical of grassroots alpine racing in the region. The event centers on a single 38 km route with approximately 1850 meters of elevation gain, starting and finishing in Lumbrein. The course follows the classic Lumbrein-Obersaxen loop, climbing through alpine terrain via the Val Mulin gorge and a high ridge traverse to Staviala Vedra, where a mountain prize is awarded to the first rider through. From there the route descends across the summer pastures (Maiensässe) above Lumbrein and Vignogn, passes the Alp Sezner aid station and the village of Morissen, and returns to Lumbrein via Davos Munts and Vignogn.

The terrain mixes technical singletrack, gravel roads, and open alpine tracks across a combination of private and public land. Conditions range from loose rocky descents on the upper ridge to fast rolling paths through the lower pasture zones. The fastest competitors finish in under two hours, and the course draws a competitive field given its place in the regional Alpen Cup series. Timing is handled through RaceResult with chip timing throughout.

Youth categories (U7, U9/U11, U13/U15) run on shorter dedicated courses, making the event accessible to families and younger riders at various stages of development. The setting in the Lumnezia valley offers a backdrop of high alpine scenery typical of the Glarner Alpen, with the upper sections of the course reaching exposed ridgeline terrain well above the treeline.