John Taranu, volunteer of the Bike Union, provides some tips in helping to reduce bike theft. John also introduces the isthisbikestolen.com app created at the Random Hacks of Kindness / Open Data Hackathon on December 5-6 in Toronto. It lets you check if the bike you're buying has been stolen.
More on fighting bike theft, see bikeunion.to/theft
How to find the serial number of a bike:
How to register a bike: