The few photos I've seen of organized city bike rides here in Baltimore, MD show mostly young, white riders. I can tell you the cycling demographics according to what I've seen over the past decade in quite a few parts of this city and some of its suburbs, but I'm not sure if you're looking at this part of the country or just CA. Also, I don't belong to any bike clubs or advocacy groups, so it would just be an account of my own observations.