bycicle

I started commuting by a bycicle.
My senior coworker who will leave our company in this month sold me the bycicle as he won't use it anymore in a new office. It was so fast so I like it.
However, I found out that it is necessary to ask him to go to a police station. It is a kind of bothering but we ought to fill a paper for the number of bycicle. All bycicle has a number for controlling so that police can check whether a rider is the owner of the bycicle. And, if the owner of bycicle changes, you should change number. So, we need to go to a police station.
When you ride on a bycicle at night, policeman sometimes comes to you and ask your name and address to check whose bycicle it is.