The “Safe Bikes” program run by SF-SAFE (the same people who sponsor Neighborhood Watch) has helped return hundreds of stolen bikes to their rightful owners. It’s FREE, secure, and only takes a few minutes to register your bicycles in the database. Safe Bikes
The chances of getting your un-registered bike back is pretty close to zero unless you buy it back at one of the auctions the police hold each year to sell un-claimed bikes.
In addition, the police cannot do much about the bike “chop-shops” without evidence that the people running these operations are in possession of stolen property.
[The only serial number on a bike is located on the bottom of the frame under the pedal mechanism.]