Community barriers to non-motorized transport are a huge issue keeping people of every age and sex off bicycles. As a side question, I'd be curious to know what fraction of women who do ride, do it only as a sport.

(That said, I live four blocks from a middle-aged man who insists on driving his road bike to the start of the club ride... three miles from his house, all of which has either a bike path, a wide shoulder, or low traffic. )