Many thoughtful posts here. Thanks. Indeed part of it has to do with wealth. Cycling as a transportation option has historically been an alternative of the poor. The rest drive cars. In addition to the poor, cycling attracts intellectuals, the environmentally conscious, the frugal rich =o) , the politically driven, those interested in fitness, and the poseurs. These are not mutually exclusive categories.

When I was in high school, I had a heavy 3 speed Huffy. Rode it everywhere until I got a car and a license. In grad school, I had a 40+ pound Motobecane I commuted on for financial reasons. The financial reasons became secondary when I really started to enjoy it. The heavy bike did not stop me from putting my son on the back and regularly riding to the top of Griffith Park to the observatory.

Almost anyone can afford a cheap road bike. Anything with skinny tires will do, so lack of money is not an impediment to riding. It's having money that keeps the masses from riding.

In the U.S. bicycling as transportation will continue to be done by the poor and those who have other agendas.