Buyer's Guide to Bike Locks

Essential equipment for the cycle commuter (Paul Smith)

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There are three things to bear in mind when buying bike locks: First you get what you pay for. Cheap locks offer cheap security: most are little more than a visual deterrent. A cheap lock is still better than no lock, but if a dedicated bike thief takes an interest in your bike, say goodbye to it. Second, cable locks that are light enough to be portable are also light enough to be broken - easily.

Only use them in conjunction with a good Ulock to secure extra bits of the bike or stuff like your helmet. Three, less is NOT more. Unlike most other bike accessories the performance of a cycle security device increases in proportion to its weight. So when it comes to portable locks it's a trade-off between how much peace of mind you want and how much metal you are prepared to lug around.

What to look for

Security ratings

Many manufacturers have their own security ratings and these can be a useful indicator of the expected level of performance. Even better though is a Sold Secure rating. Most of the major lock makers now submit their products for testing by Sold Secure, an independent non-profit making organisation administered by the Master Locksmiths Association.

There are three levels of Sold Secure rating: Gold, Silver, and Bronze and they denote the length of time a lock will hold out against escalating levels of attack from a minute against basic tools for Bronze, three minutes against more sophisticated weapons for Silver, through to five minutes against the full armoury for Gold. Gold rated locks can be more expensive but having such a lock can get you a discount on your insurance, or may be the only way you will get it.

The largest manufacturers also have their locks accredited in other countries too; the German and Dutch standards are both particularly worth looking for.

Flat or round key?

In late 2004, lock manufacturer Kryptonite came under fire on the bikeforums.net website because some of its locks could be opened with the top or barrel of a Bic ball-point pen. It turned out that the problem with some cylinder-key locks had been known since 1992, and affected far more companies than just Kryptonite. Since then, cylinder keys have all but vanished from bike locks, but the bike industry is famous for reusing bad ideas; they'll no doubt be back, and should be avoided.

D-lock vs chain and padlock

The D-shaped shackle lock is now a classic a design for bike locks. It was introduced by Kryptonite in 1972 and widely copied soon after. In effect, it's a scaled up padlock: your bike and a railing, lamp-post etc all fit inside the hoop. Well-designed D-locks, with good lock mechanisms, armoured shackles and heat-treated U-sections are tough enough that they will slow a thief down enough to make him think about picking an easier target.

However, their rigidity and bulk can make D-locks hard to carry and use. Some riders therefore prefer a loop of high-strength chain and a padlock. This combination is usually heavier than a D-lock and a little more vulnerable to attack as chain is generally easier to cut than solid bar.

Shackle

The U-shaped section that slots into the lock barrel assembly. Try to check out a lock before you buy - undo the shackle and operate the lock mechanism. Ideally at least 5-10mm of the mechanism should swing into place to hold the shackle when the key is turned. Also check the machined slot on the shackle - if it's square cut this is a potential stress and failure point if the shackle is attacked by twisting.

Warranty

An extended warranty is always good. It's not going to cover you against theft but it should be a sign that the lock won't fall apart or seize up on you.

Anti theft guarantee

This is basically a form of insurance. Anti theft guarantees inevitably bump up the price (look at the On Guards with and without) but they definitely add peace of mind into the package.

Will it fit?

There's no point buying a shackle lock that is too small to go around your bike. On the other hand, too big means you are going to have difficulty filling the shackle, and it's going to be awkward to carry around. A longer shackle should be easier to twist, easier still if it isn't filled.

Carrying it

Many D-lock makers also supply or offer a bracket to mount the lock on your bike. Definitely a nice-to-have if you're down to two candidates.

Security advice

• Always lock your bike. A lock is no good in your bag.
• Always fill your shackle or cable - any slack can be exploited.
• Always make the lock mechanism hard to get at. If it's a pain for you to unlock it's going to be a pain for the thief to get at, and being the lazy sort he'll probably give up.
• Never lock your bike to something easier to cut through than your lock such as a tree, or fence.
• Don't believe that leaving your bike on a busy street will improve its safety. Anyone who has had to cut a bike lock for legitimate reasons will tell you that people just stroll on past.
• On the other hand, never lock your bike up somewhere quiet and out of the way where a thief can really take his time. The maximum most thieves will spend trying to nick a bike is five minutes, unless you make it easy for them.
• If you commute have something more solid which you leave at work and use both your locks there - ideally use locks from different manufacturers.
• Don't leave commuting locks on railings to which you always return - you are giving the thieves something to practice on.
• A bad lock is better than no lock and a poor lock well used is at least equal to a good lock badly used.
• Always make the thief work.

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