in germany and austria you can register the bike's serial number or get a number assigned and engraved into the frame. there are different private organizations

in germany and austria you can register the bike's serial number or get a number assigned and engraved into the frame. there are different private organizations that do this, but that's enough to verify ownership. not really a solved problem though because when your bike gets stolen you still have to find it. it only helps when you actually do find it.