Stock photography, photos: A couple mountain biking Stock photos of A couple mountain biking in the evening on Donner Summit, CA. Photograph: © William Stevenson Click for a larger image and more information Keywords associated with this stock photo: biking, mountain biking, bike, cycling, bicycling, training, back country, carring, carry, morning, evening, sierra, sierras, yellow, orange, silhouette, bikers, inspiration, action, active, effort, endurance, determination, momentum, motivation, strength, aerobic, challenge, desire, difficult, adventure, mountains, distance, vista, grandeur, vastness, man, woman, summer, california, ca, horizontal, Outdoor, outdoors, outside, sports, sporting, sport, exercise, physical, fitness, outdoorsman, sportsman, adult, young, adventure, adventuring, twenties, 20s, 30s, thirties, 2, two, people, Same Sutp