Although you can usually tell at a glance whether a manufacturer is marketing a bicycle to a girl or a boy, the differences in the frames are largely cosmetic. The main distinguishing feature of a male's bike is the metal bar connecting the handlebars to the saddle, which bicycles for females traditionally lack. Increasingly, however, bicycle manufacturers are offering bikes tailored to the special needs of both the male and female physique.
The frame style of girls’ bicycles dates to the earliest years of bicycle design, when step-through frames accommodated the long skirts and dresses that women wore in the late 19th and early 20th century. To this day, bicycles marketed to even the youngest boys generally have a metal bar, while those intended for girls do not. The higher bar on a boy's bike serves to add stability to the bicycle’s frame. While not as strong, step-through frames offer the advantage of easy mounting and dismounting.
Bicycle manufacturers now cater to the needs of female cyclists, allowing for a woman's proportionately longer legs and shorter torsos, according to cycling coach Gale Bernhardt. Manufacturers may shorten the width between the handlebars of a woman's bicycle, since a female’s shoulders are not as wide as male’s. Some women's bicycles feature slightly smaller grips, brake levers and tires.
The saddle, or seat, of a bicycle may differ, depending on the sex for which the bike is designed. Men’s saddles are usually longer and narrower, while women’s are shorter and wider to support the proportionately wider female pelvis.
Sizing differences may make a particular bike more comfortable for a male or female body, but otherwise, modern men’s and women’s bicycles look remarkably similar. Advertisers tend to target either boys or girls specifically in the marketing of children's bicycles, however. While girls’ bikes feature pastel-colored paint and often have “feminine” details such as baskets and handlebar streamers, boys’ bikes more often boast dark colors and “masculine” action- or speed-oriented properties. Bicycles for older boys imitate the style of BMX bikes. Like other toys, bicycles often reflect popular cartoon or movie themes, which frequently tend to be directed specifically toward either one sex or the other, and not both.