Here’s a possible scenario: You see a Fuji Roubaix at the local flea market for only $150. This is a decent, entry level road bike that retails new for about $1000. Wow!
Serial numbers on this and many other bikes are under the bottom bracket shell (that cylindrical part of the frame between the pedal cranks), so you flip the bike over and the tweet the serial number to @IsItStolen. The bot at that account responds with “all good” — meaning the bike is registered but not reported stolen — or “I couldn’t find it” — which means the bike is not registered at BikeIndex, or “*STOLEN*”, which indicates the bike has been reported stolen.
If it’s reported stolen, you can then report the location of the stolen bike online.
BikeIndex recently reported the merger of their service with the Stolen Bike Registry, which claims 2,000 recoveries for 25,000 registered bikes.
It seems like a worthwhile service. Registration is fairly easy, especially if your bike has stock parts. Since you also list components on the bike you register, I’m not quite sure what you do if you swap out wheels and pedals for different rides. Nevertheless, it’s free so go register your bike now.