World War 2 brought about many changes to the makeup of America's culture. Many women found themselves taking on various new roles as heads of the household since most men were now enlisted and serving in campaigns throughout Europe and the Pacific. Industries changed and shifted in accordance with the demands that the war put on the economy. Steel mills became a common sight in cities as companies such as GM, Ford, and Chrysler built new mills and factories to keep up with the steel demand. The demographics of major metropolitan areas changed as these mills emerged, with many minorities taking up jobs in the mills and settling into the surrounding areas.
Change remained a constant after the war as well. Battle hardened American servicemen, influenced by the European customs they had grown accustomed to over the previous years, brought home new and interesting ideas that influenced everything from the way Americans dressed to what their vehicles looked like.
Take the bobber for example. Prior to World War 2, motorcycles had become increasingly popular. When American servicemen returned home, their popularity exploded even more so. Soldiers used their acquired mechanical expertise to design and customize bikes that were truly unique for their time. Light, streamlined bikes that had dominated the roads of the European theatre now seemed to be speeding their way across the American landscape. Anything that was seen as "extra" was taken off the bike in order to drop its weight and make it that much faster. Fenders, lights, mirrors, anything that didn't make the bike faster was ultimately ditched in an effort to increase the top speed and handling of the American Harley-Davidson and Indian motorcycles, which were much heavier than their European counterparts. These custom bikes with their lighter bobber parts were the originators of what we now know as bobbers.
For most bobbers, the front fender has been removed while the rear fender was made smaller or "bobbed." Anything considered superfluous should be removed in order to make the vehicle as light as possible.
Many people today associate the term bobber with customized vintage or modern motorcycles, often stripped of the same superfluous bits as their predecessors, plus possibly one or both mirrors, turn signals, even gauges. What differentiates the loosely defined bobber from it's well known cruiser cousin, the chopper, is that they often are more practical and built for speed and handling, retaining frame and fork geometry for proper handling and top speed, whereas the chopper is often going for style. This style can take shape as highly modified frames, extended front ends, small gas tanks; the combinations are innumerable. While the outsider may not see much of a difference between these styles, it tends to be the 'function before form' that helps identify those motorcycles that some refer to as bobbers.