A chopper is a type of custom motorcycle which emerged in California in the late 1950s. The chopper is perhaps the most extreme of all custom styles, often using radically modified steering angles and lengthened forks for a stretched-out appearance. They can be built from an original motorcycle which is modified (“chopped”) or built from scratch. Some of the characteristic features of choppers are long front ends with extended forks often coupled with an increased rake angle, hardtail frames (frames without rear suspension), very tall “ape hanger” or very short “drag” handlebars, lengthened or stretched frames, and larger than stock front wheels.[1] The “sissy bar”, a set of tubes that connect the rear fender with the frame, and which are often extended several feet high, is a signature feature on many choppers.

https://en.wikipedia.org/wiki/Chopper_(motorcycle)