[revelation]

The reason they engrave (or use multiple stickers, for carbon and others) is that the frame number is not as unique as you might think it is, certainly not unique among different producers, and always requires some central database.

You simply haven't solved the major problem here, which is one of discoverability and easy, decentralized lookup.

[FireBeyond]

"Beyond a reasonable doubt":

"So, you're claiming that this bike, which has a frame number that matches the one reported stolen, is in fact a different bike with the same frame number, one on which both producers neglected to brand in any way shape or form, and that you have no record of purchasing..."

[ethomson]

Okay, but if I report my Trek 9.9 with serial number XYZ as stolen, it doesn't really matter if Cannondale or Walmart Bikes or whomever also uses a serial number XYZ, does it?

And if uniqueness is somehow important, then the idea of local governments having some registry is just as bad. My road bike would have four of these silly municipal numbers on them from four different municipalities, about to be five. I can't imagine that this number is any more unique amongst municipalities as it is amongst vendors.

[sethherr]

Huh? That's exactly what we do solve - we offer a search that is easy to use and isn't tied to a specific region.