Types of bike lock and other locking mechanisms

Locks locked to a railing Credit: Adrian Lewis

How much to spend

It’s generally advised to spend at least 10% of the value of your bike on a lock, and, if you can, to use two different types of lock to deter thieves.

Locks are generally sold with two keys; always keep your spare key in a safe place in case your key is lost or stolen, and keep a note of your key number (this should be on the key itself or come with the lock when you buy it) so you can replace it if all else fails.

Some lock manufacturers offer warranties to replace the lock if your cycle is stolen while locked with their lock. You may have to register and/or pay for the service.


These are rigid steel locks in a D or U shape, generally very heavy and tough-looking.

The more you pay, the stronger and more secure it will be. D locks range from around £20-£80.

They can be heavy (often over 1kg), although many come with a mounting bracket so that you can attach your lock to your frame while riding.

They can be limiting in that they will not fit around all street furniture, for example lamp posts.

When you lock up, try to fit the stand, the rim of one of the wheels and the frame in the D.

By securing your wheel as well you’ll not only make it harder for thieves to take, but there’ll also be less space in the D which will prevent thieves from inserting bars or jacks into the space to lever the lock open.

It’s best to angle the lock so that the opening is facing down. This prevents thieves from pouring in substances such as glue to prevent the owner from being able to retrieve the bike, giving them the chance to force the lock open later.

Cable locks

Cable locks can vary enormously in weight and strength. They are more flexible so can be used in situations where a D lock might not fit, but thinner, cheaper versions are very easily cut through. However, thicker cable locks can be very secure.

Thinner cables are useful in combination with other locks to secure parts like wheels or your saddle so that you don’t need to remove them every time you leave your bike.

Chains and padlocks

These can be very heavy and impractical to cart around, but they are tough and a good-quality hardened heavy-duty chain combined with a couple of very good hardened padlocks may be the strongest option available.

If you need to leave your cycle locked up outside somewhere regularly you might consider leaving your chain locked there permanently, although keep in mind it might be an inconvenience to others.

Extension cables

D locks and cable locks often only allow you to lock the frame and one wheel of your bike, so you may decide to buy two D locks to secure both wheels, or to buy a cable lock to secure the second wheel.

Alternatively, you could combine your D lock with an ‘extension’ cable – a flexible cable with open loop ends which you can loop through the wheel you haven’t locked and secure to the D lock before you lock it.

Sold secure ratings

There is a three tier security grading system developed by Sold Secure (a non-profit making company which assesses security products) which is used by many insurance companies.

At the highest level are the Gold rated locking devices. These give you maximum security and may even grant you a reduction in insurance premiums, depending on your insurance provider and the type of lock; but they may be too bulky or expensive for the average user.

The Silver and Bronze levels may be lighter and cheaper but still offer defence against the opportunist thief. For the full list of locks assessed by Sold Secure visit their website.

Lock maintenance

Always take good care of your lock and key – treatment such as leaving your lock outdoors for prolonged periods can take its toll and if your lock breaks, you may find it very difficult to rescue your bike.

A drop of oil in the lock mechanism every couple of months, especially in winter, is a very sensible move.

Locking skewers or wheel nuts

If you have quick release mechanisms on your bike, it can be very easy for thieves to steal your saddle and wheels. You may wish to replace the quick release mechanisms with ordinary bolts or nuts which fit a spanner or allen key; or you can buy special locking nuts which can only be undone with a specially designed version of an allen key which is sold with the bolt.

If you’re unsure about this, your bike shop should be able to advise you and fit the replacement if necessary.

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