Why Is the Frame on a Girl’s Bike Curved?
The top bar on the frame of a girl’s bicycle is curved downward to give clearance for women’s skirts. Before ladies’ bicycles were invented, women could not ride because they were not allowed to wear pants in those early days, and their long skirts made it difficult to get on and off.
In the 1870s, someone invented a ladies’ bicycle that could be ridden sidesaddle. It was so hard to balance, however, that no one wanted to ride it. Finally, in 1884, a ladies’ bicycle with a dropped frame was designed so that it could be ridden in the modern manner.
This design has since been used in utility bikes to facilitate easy mounting and dismounting for both genders, and is also known as a step-through frame or an open frame. Another style that accomplishes similar results is the mixte.
Traditionally, bicycles with a step-through frame were known as “Ladies'”, “Women’s”, or “Girls'”, mainly for their advantage to riders:
.less risk of stretching or ripping clothes when mounting the saddle
.the rider can wear a skirt (also requires a skirt guard and possibly a chain guard)
.very quick to mount and dismount, so is suitable for delivery bicycles, or any journey with many stops
.suitable for elderly and others with restricted agility
.potentially safer than a high top tube; a rider who loses balance can step through the bicycle without becoming entangled
.compactness provides a popular starting point for folding bicycles