This community is about what is labeled "extreme sports". I personally think that name is lame, but whatever.
callmehiphop maintains this community, so leave a comment on his journal, or e-mail him at firstname.lastname@example.org.
Just because you don't partake in any "extreme" activities, doesn't neccassarily mean you can't join. If you just like them, and have stories, or comments, or just something to say. Take advantage of the oppurtunity and join.