This 34 minute film, "Killing us softly 3," regarding advertising's image of women may help explain why there aren't more women racing bikes. I encourage you to watch it and then make sure you let the women and girls in your life know that they're most attractive when they're using their smarts, actively engaging the world, and that they're much more than T & A.
I should also note, that as my friend Bev said, "If you took this as the only indicator of change, you would think there has been no progress." This is not true of course. These days, in the US, women complete college at a higher rate than men and starting salaries are equalizing, so A LOT has changed for the better. Nonetheless, watching and thinking about this will be well worth your 34 minute investment.