I was talking to a new biker recently about his decision to join a local motorcycle club. It was all new to him, so he had lots of questions about clubs in general, their colors, and so on. One of the things he brought up was whether or not it was okay to decorate a leather vest with dozens of different embroidered patches. The answer to that depends largely on the club an individual biker joins.
Most people assume that when you join a motorcycle club you bring your own vest or jacket and the club gives you the patches to mount on it. That's true in some cases, but not in all. Most of your larger, better known motorcycle clubs issue a vest (also known as the "cut") to new members along with the club's patches, also known as "colors." Both the vest and the embroidered patches remain the property of the club at all times. A member who elects to leave the club must return the vest and patches.
Clubs that issue the cut to members usually have very strict rules about what patches can be included on it. Most limit it to the colors, any patches denoting a rank within the club, and special commemorative patches (with permission). Clubs that don't issue a cut tend to be a little more liberal.
In either case you can expect at least some rules regarding how you decorate your leather vest if you belong to a club. This is solely for the purpose of protecting the club's reputation when you're out in public. As long as you are displaying their colors they expect you to protect their name and image; that includes displaying any and all non-club patches.