When your bike's out of sight, it needs to be locked. A D-lock is portable and tough.

Thieves want an easy life. To stop them stealing your bike, you need to make it difficult for them. Any lock can be broken. If your bike lock requires several minutes' work with an angle grinder, it's immeasurably safer than the lock that can be cut in seconds with bolt croppers. Sold Secure is a reasonable guideline to security. It's a bronze, silver or gold rating for locks that are submitted for testing. Locks must resist increasingly time-consuming and tooled-up attacks to pass at the relevant level. Other security ratings are provided by Thatcham, by other countries, and by the manufacturers themselves. Broadly speaking, the more expensive and heavier the lock, the tougher it will be. Police recommend spending at least 10% of the value of your bike on security for it. D-locks, also known as U-locks or shackle locks, are easier to carry than equally tough chains. You may be able to leave a lock at work to reduce your commuting load.

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OnGuard Pitbull DT 8005

Cables don't offer enough protection for use on their own. Here, however, the 10mm thick, 120cm cable is an extra, a way of securing a quick-release front wheel or seat. The main lock, which anchors the cable, is solidly-built 14mm shackle. A thief would need different tools to breach the cable and the shackle, so this approach adds security even if you don't use quick releases. The lock comes with a frame bracket, and an LED key-light that's useful for unlocking at night. Weight: 1.5kg. todayscyclist.co.uk

RRP £45.99 | Cyclescheme price £34.99

Knog Strongman

Silicone moulding encasing the Strongman will stop it clunking against your bike's frame or your commuter bag's contents, although it also comes with a frame bracket. Underneath the rubbery exterior there's a 13mm hardened steel shackle that locks at both ends, to prevent it being twisted open. The silicone covering gets in the teeth of saws or angle grinders, making them awkward to use, while the compact size – it's only 20cm long overall – limits the space and leverage for brute force attacks. Weight: 1.1kg. todayscyclist.co.uk

RRP £74.99 | Cyclescheme price £56.24

Squire Hammerhead Combi

Losing your keys for a D-lock is a nightmare. That can't happen with this version of Squire's Hammerhead, as it's a combination lock. There are six number wheels, giving a million different combinations. You can choose your own numbers, so make them memorable! It's otherwise similar to key-operated D-locks, with a 13mm hardened steel shackle and an armoured lock body. This is the shorter version, with a 230mm shackle; there's also a 290mm version. Both include a frame bracket. Weight: 1.72kg. raleigh.co.uk

RRP £54.99 | Cyclescheme price £41.24

Master Lock Street Fortum

The Street Fortum is good value for a Sold Secure Gold lock. Like other tough locks, it has a 13mm shackle that locks at both ends to prevent twisting attacks, and a pick resistant disc lock. The 210mm shackle length limits room for jacks. It comes with a frame bracket to fi x to your bike, and an integral dust cover to keep dirt out of the lock itself. As well as black, it's available in blue, red, and silver. Weight: 1.42kg.  fisheroutdoor.co.uk

RRP £39.99 | Cyclescheme price £29.99

Hiplok D

Hiplok are better known for a chain lock that fastens belt-like around the waist, making it easy to carry and quick to deploy. The Hiplok D is even more accessible: it fits a belt, bag strap, or back pocket, sliding securely in place with an integral clip. The 13mm hardened steel shackle is just 135x70mm internally, so pry-bars and jacks won't be a problem – although parking opportunities might be. It comes in cyan, red, and lime as well as black. Weight: 1kg. Sold Secure Silver. hiplok.com

RRP £49.99 | Cyclescheme price £37.49 

Zéfal K-Traz U14

Zéfal's chunkiest D-lock has a 14mm hardened steel shackle that, unlike cheap D-locks, locks at both ends. It's easy to use because of the 292mm long shackle, although you'll want to fill that space with bike or street furniture for maximum security. Like any lock, it will need occasional oiling. However, the lock mechanism is protected against dust and corrosion. It comes with a frame bracket. This lock hasn't been tested by Sold Secure; Zéfal rate it 4.5 out of 5 on their own scale. Weight: 1.6kg chickencycles.co.uk

RRP £31.99 | Cyclescheme price £23.99

Abus Granit X-Plus 54 Mini

This is a smaller version of the highly-rated Granit X-Plus. At 15cm long, it's small enough for a back pocket or bag. The shorter shackle means the bike has to be parked right up against its anchor point, which is less convenient but more secure; there won't be room for a thief's bottle jack. It's a hefty 1.5kg despite its size because it's so solid. It uses double locking mechanism and a 13mm hardened steel shackle, with a square section to prevent it being twisted open if one side is cut. Sold Secure Gold. zyro.co.uk

RRP £79.99 | Cyclescheme price £59.99

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