How to change the bicycle registration?

1. You can go to any bike shop that take care of bike registrations.

2. You have to bring your bike, I.D., and 600yen.

You will also have to bring the following if your bike was given to you by a friend,

「 自転車の譲渡を証明できるもの（譲渡書、防犯登録カード「お客様控え」等

http://www.bouhan-net.com/information/present.html
which say, any document which you can show the transfer, such as the note which the last owner gave the bike to you, or registration card which you get at the former registration,etc.