KZ Krono is a late-May uphill race in Santurtzi, Bizkaia, focused on a short, steep push toward Mount Serantes. The primary running option is about 3 kilometers, climbing roughly 400 meters, making it more of a vertical-kilometer effort than a typical road or trail race.
The course begins in Plaza de Kabiezes and concludes on the summit of Serantes. Adults can compete on foot or by mountain bike; the BTT course covers 3.5 kilometers with the same 400 meters of elevation gain. Children have their own short “Txiki” events: 600 meters for running and cycling, with climbing remaining a key element of the challenge.