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

You answered correctly. In Germany, motorcycles must be submitted for the main inspection (Hauptuntersuchung) every two years. This rule ensures that motorcycles remain roadworthy and meet safety and environmental standards. The first inspection usually takes place two years after the vehicle’s first registration, and from then on, inspections continue every two years. Regular inspections are important to catch technical problems and keep riders and other road users safe. The other options, such as every three years or only during re-registration, are not correct according to German traffic laws.