Climbing onto a bicycle with a large front wheel took skill. Once the rider was on, a smooth road was important in order to stay on. This invention replaced "bone-shakers," or cycles with 2 equal sized wheels and no pedals. These bikes were known as "velocipedes" and were introduced in the 1870s. They were usually ridden by men simply because women's clothing was not right for riding with a leg on each side of the bicycle. Then too, some forms of exercise were still not proper for women in the early 20th century. Riding such a bicycle was dangerous; the roads were bumpy and falls were common.