What's the advice of the cycling forum on this?
Media reports constantly repeat anti-theft advice to register your bicycle without any details of how.
So far as I can find there is no official national bicycle register.
A private company of unknown credibility claims to "work in partnership with the Gardai[sic]" and invites people to provide a fair amount of personal information on bikeregister.ie.
The Gardaí do ad-hoc bicycle registration from Bridewell and Donnybrook Garda stations at infrequent ceremonies around Dublin city.
I already have my bicycle, including frame number, registered with the manufacturer for warrenty purposes. Should I do more?