Huge potential for factory getting number wrong in each place. They could do it, of course, but I would imagine it could easily add £20 to retail price.
I must admit I have never considered anti theft measures when designing a mountainbike frame. Perhaps I live in cloud cuckoo land though?
Surely if you are that worried, one of them tracker chip things down the seat tube is the best bet?
Surprised there's such a big potential as I thought it was a bloke with a "stamp". Bash it into the frame twice (or more) rather than once. I'm also surprised you think such extra work would cost c.£10 or £15 at the manufacturers. However, I don't design / get bikes made so I'm suggesting without thought for or knowledge of the implications
Imagine bikes with the number in a couple of places and legible. Any time someone flogs a frame they either put it on the ad or get asked. If number is recorded during original sale it starts to become a good and reliable way of tracing / demonstrating ownership.
Frame numbers are good because they don't demand separate kit. Chips are only as effective as the number of scanners and the number of coppers using them. I suspect that's very few.
It's almost like a registration but as it's the factory mark that's already applied there's little of the hassle of a proper registration system. Sure it's got to be recorded at point of sale but that isn't such a big thing. Alternatively the owner just keeps a record / photo.
I had 3 bikes nicked last year. Lots of bikes look the same, expecially once they're stripped down. Plus, a dent or scratch might be unique and well know to the owner but I bet they've not got much proof apart from memory. Plus, if / when something similar is recovered X months later can it be remembered? Plus, what do coppers put through a database or whatever? My 2006, TNT, metallic blue and silver Turner 5 Spot with specifically upgraded RP23 (PUSH tune) was unique to me. I imagine to the average copper it's just a blue and silver bike with bounce both ends, if that. If there's a reliable number on it then plod can just bang it into whatever database they use, just like serial numbers on laptops etc. Sure, you can grind and disfigure one number with the reasonable excuse that it's wear and tear, especially under the BB. But to do the same in two locations is a clear sign it's probably dodgy.
Maybe as well, if it becomes easier to identify a bike by the number and harder to make such numbers unrecognisable, therefore, harder and less profitable to flog, maybe scrotes wouldn't see them as such a lucrative thing to nick.
I'd never worried about locks, chains and alarms before but once someone has it away with a few grands worth of your stuff you start to wonder how to make it harder for the ***** and how it'd be easier to catch them.