Watch Sadisflix. Six novice riders-father, sons and friends-take on the Colorado backcountry on BMW F800GS adventure bikes to create a film about life, meaning and the longing to be part of something epic that is written on every human heart. John Eldredge, author of the New York Times best-seller Wild at Heart (4 million copies sold) and his three sons are joined by two friends for a thousand-mile ride through the best dual-sport tracks the Centennial State has to offer, serving up a thoughtful documentary on life's deepest questions.