Like any crime. if your bike goes missing, no cctv/no witnesses, not allot to do other than give it a crime number and take details of things like frame no. in case it turns up.
Like any crime, if there is CCTV, or witnesses, then these will/should be seen, and any investigation will go from there.
The Police are now required to record crime accuratly under the NCRS (National Crime recording Something........Standards) and like anything to do with statistics, if that crime can be solved, its a plus figure on the Police's books.
If you become a victim, don't be afraid to ask how the investigation is going, and pester the cop. Also, do a little digging of your own, if you identify CCTV, the cop is hard pressed to 'miss it', and therefore you are more likely to get the cop to look at it. (hope that makes sense)