Which vehicles are not allowed to use a road sign-posted like this?

The sign shown prohibits the use of motorcycles on the specified road. According to German traffic regulations, this sign indicates that a restriction applies specifically to motorcycles, meaning they are not allowed to enter or use that road.

To fully understand this, it's important to recognize that traffic signs can symbolize restrictions that apply to various types of vehicles, including motorcycles, cars, and trucks. In this case, since motorcycles are directly depicted on the sign, it indicates their prohibition.

Understanding these signs is crucial for ensuring safety and compliance with traffic law, as ignoring them can result in penalties or unsafe situations. Always pay attention to the specific vehicle types mentioned in road signs to avoid confusion and ensure safe driving practices.