An outlaw motorcycle club is a motorcycle club that is not sanctioned by the American Motorcyclist Association (AMA) and does not adhere to the AMA's rules. Such clubs are sometimes known as a motorcycle gangs or biker gangs. In the United States, outlaw motorcycle clubs sprang up after World War II. Members rode Harley-Davidson cruisers and choppers. Outlaw clubs celebrate freedom, nonconformity to mainstream culture, and loyalty to the biker group. The clubs have their own sets of bylaws from which the values of the outlaw biker culture arise.