I think you’d have to look at it as to what ‘mode’ of cycling you are looking at: Utility, Racing/Sport, Recreational. I think the answers are different to each of those questions for each category. On the general subject, I found this post from Behooving Moving interesting. “There is no logical imperative for saving the planet, yet many logical reasons to cycle” http://bit.ly/dq6hhu

Perhaps the only “specific” that shows up in this set is what appears to be an underrepresentation of people from non-European ethnic groups (a problem which I believe both Netherlands and Denmark have been attempting to address). Though when I travel to Amsterdam these days where I stay in the east end (Indischebuurt/Dapperbuurt area) is extremely cosmopolitan and there are cyclists of many “visible” origins, and one sees people in African and Middle Eastern clothing, girls cycling wearing Muslim headscarves etc.

I certainly haven't noted much difference according to age, gender or social class: people in the posh area south of Vondelpark certainly cycle, and I've seen lots of bicycles in more working-class suburbs as well.

Love the “variety”.