Bicycles/Equipment and Accessories/Locks

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Whereas some bicycles are never left unattended, most owners are away from their bikes for a significant amount of time. It is a fact that, in all countries, many bicycles are stolen each year, even from public areas, and that despite bicycle marking and registration very few are ever recovered by police.

The best way to avoid the theft of a bicycle is therefore to keep it within reach at all times, but for those who cannot, there are no substitutes for common sense and a good lock.

An instructive video that summarizes many of the hardware and locking method risks can be seen at YouTube: How to steal a bike

The Bicycle Thief[edit | edit source]

Security is not all about locks. It is about not having your bicycle look like the easiest mark. It is best of all if the bicycle is not in the thief's domain at all; that is, better locked up at home. After that, assuming that it must be in some public place, it must be secured. But not only that. In fact, it has to be made to look like a don't bother choice to a thief compared to any bicycles nearby. To labor the point, thieves are looking for the easiest jobs, and there are enough of these around without extra work. If the locality is difficult for a thief to work in, then so much the better. Consider the following points.

  • Thieves or their observers often loiter nearby. If you have the impression that somebody is loitering near a bicycle, or passing by a bicycle a bit too often, then thefts may be imminent. Trust your judgment and find another location for yours.
  • Thieves do not usually pick locks. They use breaking tools. Alas for the thief, most of these methods, although effective in many cases, are very noisy and attract much attention. For this reason, an adequate lock that resists the most opportunistic set of thieving methods, cutting and mechanical force, is often just as useful as a top-line lock. A wide range of locks is evaluated by agencies listed in the section below, where most locks have been given one of Bronze, Silver, or Gold ratings for resisting attack. Thieves will at times be found variously with wire cutters, bolt cutters, hack saws, car jacks, freezing sprays, and perhaps lock raking tools.
Figure 1. A low cost u-lock cut with a hacksaw.
  • Do not leave a bicycle too long in one place. A bicycle that has been standing in one place for longer than the standard shopping time suggests to a thief that the owner is away for the immediate future. This allows him freedom from interruption. Try to avoid this, even in a public area. Cyclists who leave their bicycles at railway stations while they take trains need more than the usual care.
  • Lock a bicycle in an area with lots of pedestrians. A public area with lots of meddling pedestrians is always more troublesome to a thief than one without. Pedestrians increase the chance of their activities being reported, though vehicular traffic alone is no protection, since drivers will rarely interrupt their journeys for things outside of their vehicles.
Figure 2. A typical cable lock. The cable has been cut with bolt cutters.
  • Do not use a cable as your main lock. Any wire cable, as a combination lock, a keyed lock, or with a padlock, attracts a thief. Any such item is easily cut with wire or bolt cutters. The use of such tools attracts virtually no attention. At times, especially for thin cable locks, just pulling the bicycle against such a lock is enough to break it apart. Thick bars of hardened metal are needed to resist bolt cutters, while softer metals might still fail. See Figure 1.
  • Use two locks instead of one. A thief is looking for an easy theft, so a bicycle with two non-cable locks instead of the more usual one is rarely targeted. Lock the bicycle through the frame. That is to say, through any triangle in the main frame that does not come apart. Of course this does not protect the wheels, especially if they are quick release. In this case, consider locking the front wheel to the stand with the second lock, and the rear wheel and frame with the other. Running a cable through both wheels to your main lock might also act as a deterrent if a second u-lock is out of the question.
  • Do not depend on street cameras.The thief might not be put off by cameras, especially if he does not return to the area often, or is an addict. Street cameras in any case are more likely directed at illegal parking for their revenue value, rather than the bicycle stands where thefts take place.
  • Make the lock position awkward for the thief. Some thieves will cut a bicycle cable while seeming to struggle with their own bicycle lock on the other side of a stand. Parking where there is no room for his bicycle might avoid this.
  • Always lock to a solid immovable object. Do not rely on ring locks alone. Make sure that bicycle stands or poles are not sucker-stands, that is, ones that can be lifted from the ground, or unscrewed to release the bicycle. Such stands do exist and make life too easy for the thief. Cast iron railings, although they look solid, are brittle and can be broken with the blow from a hammer. Avoid these too.

Lock Types[edit | edit source]

Figure 3. A typical high-end U-lock with a strong shackle, also known as a D-Shackle.
Figure 4. A folding lock. This lock closes into a flat pack when not in use.
Figure 5. A ring lock. It locks the rear wheel to the bicycle frame, but does not secure the bike to the stand. Bike rentals use these.

There are various types of bicycle locks sold in the marketplace. The following includes the more common.

  • Cable locks, with keys or combinations. See Figure 2. They consist of a steel cable terminated in a lock section. Sometimes the lock is opened with a key and sometimes it uses a number combination. These locks tend to be low cost and are of light weight, but as mentioned in an earlier section, they are the most vulnerable to cutting with wire or bolt cutters. Some individuals claim ability at opening combination locks using the feel of the tumblers. Some examples of cable locks have additional reinforcement around the main cable and this tends to upgrade the attack tool required from wire cutter to bolt cutter.
  • Chain locks. These replace the steel cables of cable locks with hardened steel chains. The thicker the chain links the better. These are commonly cut with bolt cutters.
  • U-locks, also known as D-Shackles. See Figure 3. This is perhaps the lock type to choose. They are available from many manufacturers. They consist of a u-shaped shackle that fits into a detachable lock section. See the adjacent image. They are most often key operated. Good examples have the following characteristics:
    • Hardened steel shackle and lock blocks Hardened steel resists hack sawing, and cutting with bolt cutters. Strong blocks and latches resist the use of jacks and levers to break them.
    • Thick shackles. This figure applies to the steel alone and excludes any coatings. The thicker the steel the better. Useful lock items commonly have 12mm to 14mm shackles.
    • Two dead lock fastenings. Dead lock means that the catches in the lock block are not sprung like a Yale lock on a door, but rather like a door mortise. These cannot move without the key. If they are sprung, they are prone to shimming attack, namely the pushing of a thin metal sheet between the shackle and the block to release it.
    • Twist resistance. This means that if the shackle is cut once, it should be difficult to twist the broken parts enough to remove the lock. Such a lock should ideally need two (noisy) cuts of the shackle with an angle grinder to release the locked item. Some locks that claim such properties can be separated after a single cut.
    • Rated appropriately by a recognized testing agency. The best locks are rated by agencies like Sold Secure. Locks that have not been rated by such an agency are best ignored.
  • Foldable Locks. See Figure 4. These items fold into a flat pack and open into a hinged loop of metal bars. The thicker and wider the bars the better. Soft steel versions exist that can be cut with bolt cutters, and some well known makes are weak in their hinge fastenings. Refer to YouTube for examples.
  • Ring Locks. See Figure 5. Unlike the locks so far described, these locks do not lock a bicycle to an immovable object, but are used to lock the rear wheel to the bicycle frame. They do not therefore prevent a bicycle from being lifted onto a vehicle and stolen, but might still be useful as a second lock in combination with say, a U-lock. They are used by some bicycle rental companies.

Avoiding Paint Damage[edit | edit source]

Most locks, especially d-locks, have a rubber coating to minimise damage to the bicycle's paintwork. Unfortunately not all locks have such coatings and even when they do, the repetitive positioning of such locks can cause semi-permanent marking of light paintwork. To keep a new bicycle's paintwork as near perfect as possible, there are two methods that might help.

  • Apply removable skins at an early stage, to the parts of the bike that come into repeated contact with your lock. The operative word here is removable, since some skins cannot be easily removed. At least one type peals off easily and can be cut to size.
  • Soft-coat a d-lock's shackle. One trick that works well is to stretch a finger bandage over the entire shackle. Supplied in rolls, this tubular bandage can be cut to length, and can be renewed as often as necessary.

Bicycle Lock Brackets[edit | edit source]

The lock is mounted on the bicycle with a bracket that is supplied with the lock. However, it should not be assumed that the bracket supplied will be suitable for every bicycle. Purchasers commonly complain about these.

Figure 6. Shows a simple method of mounting a Brompton bicycle lock by sliding it through the seat rails and suspending it to the rear rack. A cheap alternative to expensive luggage.
Figure 7. Shows how to front-mount a bicycle lock to the steering column of a small folding bike. A tapered steering post causes slight looseness but still works ok.

For example, some locks like those made by Abus often hold the lock block in place, while those of Kryptonite hold onto the shackle. There are layout consequences for these methods, and they are not always easy to see in advance. Even owners of full sized bicycles of a conventional upright style will find cable runs or other obstructions to their first choices. A lock with a long shackle might be more difficult to find a place for than one of normal length. Intending purchasers might well study how others handle such things on similar bicycles to their own before making a choice, and don't forget to see what riders are saying on the web.

Lock mounting positions are notoriously poor for folding bicycles where much of the designer's attention has focused on the compactness of the fold rather than the mounting of accessories. While some folding bicycles have baggage mounts, they are never universal, and only that manufacturer's expensive luggage is likely to fit. Three cheap alternatives that work well enough in certain circumstances are:

  • Tie a child-size 30 cm rucksack from the side of the bicycle's rear rack. Just string the short straps through the rack then tie them after passing them through the bag's carrying loop. Any unneeded straps can be removed. Such a cheap item is a perfect fit, keeps the lock dry, and because it will be empty whenever the bike is parked, can stay tied to the rear rack without fear of theft.
  • Hang your u-lock shackle from the seat springs. Then, bungee-cord the block section to the rear rack, or just let it hang. This method works better than it sounds, and is a life-saver on a Brompton. Long shackles however might be a bit long to hang, unless the rear rack method is used. See Figure 6.
  • Mount the lock on the front steering post. Bicycles with a long steering post have enough room to slide a lock onto a mount, (See Figure 7), but others like the Brompton will not.

Replacement Keys[edit | edit source]

Figure 8. Three basic ways to lock a bicycle to a stand. A. Frame and rear wheel together. B. With an additional lock for the front wheel. C. With a cable between the shackle and front wheel. Many other methods exist.

A key lanyard of the kind that attaches to an eyelet on clothing avoids virtually all key loss. However, despite best efforts, keys are sometimes lost and replacements are needed. The means of obtaining such keys is rarely clear and lock manufacturers for the most part are slow to advise their customers on how this can be done. Consider these points.

  • Key numbers and key cards. There are two kinds of key numbers.
    • When there is a key card issued, it has a unique number. This number is used by a locksmith to make the cuts in a key. It is quite often the bitting code, that is, the code used to program the cutting machine, but might require further lookup. When a key card is issued, the keys themselves are unlikely to have any numbers on them.
    • Numbers on the keys. Such numbers are usually a blind code. That is, when only that number is given to a locksmith he must use it and a proprietary look-up table to obtain the bitting code to make the key. Although, if the key itself is given to the locksmith, he might well be able to copy the key, subject to the complexity of the task.
  • Some key types can be replaced by local locksmiths. These are most usually those whose cuts resemble those of house keys. In these cases the locksmith will make copies by copying an existing key. Such keys are usually found in lower cost bicycle locks.
  • Some replacement keys are supplied only by the manufacturer. There are different methods in use. Here are three.
    • Abus. This manufacturer most often supplies TWO keys for each bicycle lock. Purchasers of locks can register their key numbers against future orders. Keys could use key cards or have key numbers. In the United Kingdom, replacement keys are ordered only at selected retailers, (e.g. Evans Cycles, etc.), whereas Canadian and United States lock owners would appear to have access to direct on-line purchase. Locks delivered with a key card require that number when ordering spares, while others, notably those whose keys instead have a number on them, do not. The time to fill orders in the UK has been known to be several weeks.
    • Kryptonite. This manufacturer most often supplies THREE keys for each bicycle lock, but sometimes only TWO. Recent keys have numbers on them. This manufacturer also allows key registration, and their web page implies that spares can be ordered directly on-line, even in countries other than the US. Some of their lock choices allow the first two replacements free of charge. No information is available on the time to fill orders.
    • On-Guard. This manufacturer most often supplies FIVE keys for each bicycle lock. Key registration is seemingly available for only customers in the United States, and the way to replace keys, if at all, is unclear from their on-line site. Their registration page uses key card numbers only.

Quality Rating Standards[edit | edit source]

A number of organizations have evaluated bicycle locks for their quality and resistance to attack. Often such testers place certifications on product packages to assist in selection, and most have web pages and catalogs that are quite comprehensive. The following few are among the most well known.

  • Sold Secure. Interested parties can download their catalog from their web page at It contains locks of all types, including bicycle locks, and their ratings. They rate each product as one of Bronze, Silver or Gold.
  • Thebestbikelock. This web page, although lacking the same status as Sold Secure produces a useful tabulation of current bicycle locks with their properties, including relative weight, dimensions, a score of their own, and that of others. Find the site at
  • Stichtingart or just ART. This site is a Dutch testing agency and their site is in Dutch too. I cannot find an English site for it but their tables are fairly self explanatory. Use the field marked Merknaam en type to perform searches; Google Translate will no doubt bridge the gap for those who need more clarity. Find them at They have good listings with photos of products too.

Bicycle Locking Behavior[edit | edit source]

It is of course the behavior of cyclists that allows thieves their perpetual lifestyle, but in part, the theft of bicycles must be to do with the cost of good locks. Table A shows the locking habits for a fairly typical bike stand installation at an underground railway location in the United Kingdom. Such parking times would likely be of a few hours.

  • About forty percent of riders left their bicycles with cable or chain locks. About half of these cable locks could be cut with wire cutters and the remainder with bolt cutters.
  • About sixty percent used a u-lock. Only fifteen percent of these used a cable with their u-lock for the wheels. Although the thinnest shackles might be cut with bolt cutters, the majority of these would need much noisy angle grinding to steal them.
  • Nobody used two u-locks. This despite the fact that bicycles locked with two u-locks are rarely stolen.
Table A: Bicycle Locking Methods
Observed near a London, UK Underground Station 24 July 2017
Type of LockingNumber FoundPercentage of Total
Cable Lock
Includes both combination locks and keyed locks
Some simple, some reinforced.
Chain Lock
Includes combination locks and keyed locks
Some with padlocks.
Folding Lock33%
Of all quality levels.
Most with at least a 12mm shackle.
U-Lock plus Cable
Of all quality levels.
With the cable used for wheels.
Two U-Locks00%

Suggested Best Method[edit | edit source]

The following is the method recommended for the general case.

  • Use a good u-lock and cable. See Figure 8. Cable the front wheel to the lock and use the lock to fasten both the frame and rear wheel together to an immovable bike stand. Alternatively, lock the frame to the stand and run a long cable through both wheels to the lock. The deterrent value of a second u-lock should also be considered.
  • Buy bicycle insurance Consider this especially if your bike must be left for several hours at a time, or left in a fairly quiet locality. There are several bicycle insurance schemes available in most countries. They include both those offered by bicycle retailers and those that form a part of household insurance. These policies commonly provide new for old replacement bicycles if they are stolen.

See Also[edit | edit source]

External Links[edit | edit source]