Bike Locks

U-Locks: This widely used style offers your best deterrent. The bulky locking mechanism resists hammers, chisels and the like. Its horseshoe shape can limit leveraging-provided it's not oversized for the bike. The goal is to reduce the amount of space in which a thief can insert a crowbar and leverage enough force to pop it apart. U-locks come in various sizes. 

Cable Locks: These are versatile and adaptable but generally offer less theft deterrence than U-locks. They are a good choice to use in combination with a U-lock to secure easily removed parts (e.g., seat). Many have integral locks; others require a separate padlock. Some feature sliding sizing or an armoured coating. A few newer models feature stylish designs and even come in colours!

Chain Locks: These locks use a specially designed chain link that disallows leveraging and resists hacksaws or chisels. Be sure to invest in a padlock that's just as sturdy as thieves can easily cut through thin locks, no matter how sturdy the chain. The downside? Chains are heavy and bulky, so they are best for stationary uses.

Wheel/Seat Skewers: Quick-release wheels and seat posts are, unfortunately, as convenient for thieves as they are for bike owners. Locking skewers disable the quick-release feature and make it a lot tougher to steal. They're easy to install but require a special wrench that comes with the skewer.

O-Locks: These are designed to stay mounted on the bike. Modelled after the concept of wheel clamps placed on illegally parked cars, O-locks simply stop the wheel from rotating. They are generally too small to be attached to fixed points such as a signpost, so are less secure than other choices.

Cuff Locks: Just as the name implies, cuff locks can attach your bike to a secure post. The middle hinge is specially built to resist tampering.