Ely Blue at Grist wrote an article last week trying to explain why women haven't become a larger percentage of bicyclists over the last 20 years (they've remained around 25% while adult men have increased and children have decreased). [She said the number of women cycling in Chicago has decreased but that's not quite right. She means the percentage of women who commute to work by bike in Chicago is decreasing]. While she doesn't dismiss the usual fear and fashion theories for this, she also thinks the economy is to blame.
Women are more likely to be poor, and the poor are less likely to bike, ergo women are less likely to bike goes her logic. It's not without validity, but it could go the other way - Women are less likely to bike and the poor are more likely to be women, so the poor are less likely to bike.
She also notes that women do more housework and so they have less time to bike; and that they tend to make more trips and more diverse types of trips than men, which makes biking impractical.
Bicycling is, in much of the car-centric U.S., either a privilege or a punishment. That's why more women aren't bicycling. It isn't because we're fearful and vain; it's because we're busy and broke and our transportation system isn't set up for us to do anything but drive.
She may have oversimplified the time use element, but still come to the right conclusion. Women do do more housework per day, but men on average spend an hour more at work. Women need about 20 minutes more sleep than men and spend an extra 16 minutes a day on personal care, so it all gets pretty complicated. Still, the critical fact is that men have about 42 minutes more per day for "Leisure and Sport" and that could bring bike commuting into reach for more men.
Meanwhile the Association of Pedestrian and Bicycle Professionals has done some surveys on this very subject. It certainly seem time is a major issue.
Angie Schmitt of Streetsblog has a different opinion
I think the problem for a lot of women is that on some societal level, bicycling is at odds with many of our ideals about what it means to be feminine. I would argue that the fashion explanation shouldn’t be discounted. There is a certain percentage of women who just aren’t going to leave the house in the morning and enter a business setting without a pair of high heels. And it’s not because these women are vain; they are adhering to a social norm. And the business world, and society in general, can be harsh to women who don’t conform.
The high heeled shoe is a symbol of femininity in America. And the fact that they prevent women from being physically active isn’t an accident. They help embody this aspect of traditional femininity: women aren’t supposed to be physically active, at least in a public setting.
I would add another, small factor, which is that I was able to bike to work every single day my wife was pregnant and was back on a bike the day after she gave birth, I doubt she would have been able to pull that off.
Mrs. Washcycle very much embodies the list of concerns here. She will bike (other than recreation) if it is faster than all other options, she won't feel threatened by cars and she will not be sweaty when she gets there. That creates a donut of locations around our house that is not so close that we should walk, but not so far that we should taxi/metro/drive.