Vorbau

Vorbau is a German term that translates roughly as “fore structure” and is used in several technical contexts. The most common meaning in everyday language and in cycling refers to a bicycle component, while in architecture and construction it can denote a projecting front part of a building or an attached front section.

In cycling, der Vorbau, or the bicycle stem, is the component that connects the handlebars to the steerer tube of the fork. It serves as the link between the rider’s steering input and the front wheel, thereby influencing riding position, reach, and steering geometry. Stems come in different forms, with quill stems inserted into the steerer tube and secured by an expander mechanism, and threadless (ahead) stems that clamp around the steerer using pinch bolts and spacers. They are made from materials such as aluminum, steel, or carbon fiber and are available in a range of lengths and angles to adjust comfort and handling. Proper installation and torque are important for safety, and stems should be inspected for cracks or loosening.

In architectural and construction contexts, Vorbau can refer to a projecting front element of a building, such as an exterior front piece, entrance projection, or vestibule. The precise meaning is context-dependent and may vary by regional architectural terminology. In general use, Vorbau denotes an added front portion or mounting that extends from the main structure.

The term Vorbau thus covers both a specific mechanical component in bicycles and a broader architectural concept of a projecting front element, with meaning shaped by the discipline in which it is used.