I'm involved with the bike co-op here in my city. Co-ops vary a lot between place to place; different co-ops have different cultures and goals. The co-op I joined started out as an offshoot of Bikes Not Bombs, but over the years has become less focused on specific programs/community initiatives and more on providing a space for everyone to come in and work on their non-motorized transportation. If you want to know what your co-op is like, the best way to do it is go and ask them. Every day we're open we have a few people come in and say, "hey, I've never worked on bikes before, but I'd like to learn," and we put them to work doing something useful and educational.