The best way to protect yourself against bike theft is to park your bike in a secure bike parking facility. Many workplaces have bike rooms or cages, and some TransLink stations provide lockers and parkades. Other good choices include monitored parking facilities and bike racks in a high traffic area.
*Record your serial number
It is often on the underside of your pedal (crank) shaft, and keep it in a safe place.
There are websites available to register your bike like the National Bike Registry and with your local police department. It alerts others that your bike is stolen and helps police recover and return it to you.
Use a good lock. Don't use a cable lock as your primary lock. They can be easily cut. Use a high-quality U or folding lock. Size matters. Smaller U-locks are harder to break.
Don't just lock the wheel to the rack. That leaves the rest of the bike vulnerable. Lock both the wheel and the frame to the bike rack.
Don't leave your bike out overnight, or in places where it looks like you'll be gone for a while. Whenever possible, take your bike inside with you.
If locking your bike to a pole or parking meter, make sure that it's firmly screwed in. Try to only use bike racks in busy areas and take any bags or lights with you. Vancouver police recommend avoiding poles and parking meters altogether because bolts can be removed, and the heads of the parking meters come off easily.
Consider switching out quick release components on seats and wheels for bolts.