It is believed that women are more sensitive to safety and convenience issues than men when it comes to bicycling. If cycling is made safe and convenient, as in Europe and Japan, then perhaps more women will participate in North America and Australia.
When cycling is encouraged as an everyday transport, with safe bike lanes and more upright bicycles, with a greater carrying capacity, then it seems more accessible for women of all ages. Sport bikes, common in North America and Australia, have a more bent over posture, which encourages young men and women but not older ones. Read more here. Or contact the author.