The three types of bike lock
The D-lock (also known as the U-lock) is strong and can be carried attached to the bike frame or a rack. Locks with round keys are easily defeated; modern ones have flat keys.
A cable is the most easily defeated type of lock and should not be relied on to secure the frame. However, it can be useful for securing other parts of the bike.
A chain is versatile and can be stowed in cycle luggage or around the top tube. However, it will be heavier than a D-lock of equivalent security level. When buying a chain, look for one with square section links as these resist bolt croppers better.
Two good locks
The best advice for locking a bike in an urban area is to use two good locks of different types and to ensure that the frame and both of the wheels are locked directly to an immovable object (such as a Sheffield stand). Using two types of lock is advisable because each type requires a different tool to break it and bike thieves tend only to carry one tool.
How much to spend on a bike lock
A budget for bicycle locks should be no less than 10% the replacement value of the bike. For instance, if the bike and accessories would cost £500 to replace, at least £50 should be spent on locks, preferably more.
How do you know if a bike lock is any good?
The UK has a lock rating scheme, administered by the Master Locksmith’s Association, called Sold Secure. Sold Secure tests how difficult it is to break a lock and then issues a rating for that model.
Sold Secure locks are rated from one to fifteen, with fifteen being strongest. For quick reference, Sold Secure locks are also categorised as bronze, silver or gold. Bronze rated locks range from level 1-5. Silver rated locks range from levels 6-10. Gold rated locks range from levels 11-15.
- A searchable database of Sold Secure approved locks can be found at the Sold Secure website.
- A PDF catalogue of locks with Sold Secure ratings can be downloaded here.