Is it illegal to install the tailbox?

In the streets and alleys, you often see some motorcycles behind will install a rear tail box, the installation of the rear trunk will facilitate people to put some personal belongings, let's talk about the installation of the rear trunk is illegal?
Although motorcycles only have two wheels, they are also included in the ranks of motor vehicles, and when running at high speeds, they need to pay the same fee as cars, and they also enjoy the treatment of motor vehicles. Is it a violation to put a trunk on a motorcycle? Traffic police: Tell once! We all know that it is not allowed to modify cars without permission, even if they are to be modified, they must be modified according to requirements and standards, the same is true for motorcycles, and it is illegal to add a trunk at will. Such a statement has also caused the dissatisfaction of the majority of motorcycle friends, motorcycle plus a trunk is nothing at all, many motorcycle friends are migrant workers, usually go home to visit their wives and children, definitely need to buy something, buy daily necessities directly on the handle of the motorcycle, will also affect the operation and driving, install a small trunk can also put something, can be described as very convenient.