The Secret Website
Some biker gangs are old enough that they are considered as organizations now, where they sell stuff, have events, and arrange different gatherings. While most of the gangs from the famous one-percenters are involved in crimes, they too have an organized system of work.
For example, the Hells Angels have a secret website that is accessible only to their members. No one else can access the website unless that person is friends with someone who is a gang member. If getting entrance to the website is so tough imagine what it would be like to join the club itself.