Here’s why it’s a good idea to (1) write down the serial number on your bicycle and (2) if stolen, report it.
It’s worth also taking an original photo of the bicycle to share publicly and another with you in it for Gardai (police). One good way is to email yourself the photograph, serial number and bicycle details — archive the email and search for it if needed.
When the owner went to Gardai and explained that they had found the bike, officers confirmed their story and then traveled to the spot where the new “owner” had locked it:
And it ended well: