Ball-type rear towbar bicycle frame. Many vehicles can be equipped with a 50mm diameter trailer ball at the rear. This is the European universal trailer ball standard. The role of the trailer ball is not only to tow motor homes, motorboats or other equipment, but also to carry the bicycle frame. It is usually installed on high-end SUVs, MPVs or high-end business vehicles, and is popular with business people and women customers.

The frame component is the basic structure of the bicycle, and also the skeleton and main body of the bicycle. Other components are also directly or indirectly installed on the frame. There are many structural forms of frame components, but they can be divided into two categories: men's frame and women's frame.