When must motorcycles be submitted for official inspection (Hauptuntersuchung)?

Motorcycles must undergo an official inspection, known as Hauptuntersuchung, every two years according to German regulations. This requirement ensures that the vehicle meets safety standards and is roadworthy. Additionally, whenever a motorcycle is re-registered—such as after a change of ownership or a significant modification—it must also be inspected to verify compliance with safety and emissions regulations.

Thus, the combination of both options—every two years and every time they are re-registered—is important for maintaining road safety and ensuring that all motorcycles comply with the latest standards. It's vital to follow these rules to prevent accidents and ensure the safety of all road users.