If you are trying to use a image on a modern iPhone:
Deep oranges and long shadows to emphasize trail texture. 1920x1200 Mountain Biking – HD iPhone Wallpaper...
Mountain biking imagery often features high-contrast landscapes, trail action, or close-ups of gear. If you are trying to use a image
1920 pixels is high enough for a sharp look on most Retina displays. 1920x1200 Mountain Biking – HD iPhone Wallpaper...