Bike Security

Security Review: Bike Security

A well secured bike.


The aim of bike security, predictably, is to prevent bike theft. Cyclists often need to leave their bikes to enter buildings or other areas where having to carry a bike around would be impractical. Bike locks are common devices used to prevent bike theft. Thieves can target specific parts of the bike (e.g. seat, wheels) or attempt to steal the whole bike. There are various types of locks designed to prevent these different forms of theft. The most important features of a bike lock are strength (or resistance to breaking), portability, cost, and ease of use. Because there are different kinds of bike theft, not every lock will excel in each of these areas, and depending on the thief, some of these locks may even be completely ineffective. It is important for locks to both deter casual thieves and resist attacks from more skilled thieves.

Threats and Weaknesses

Both thieves and types of theft are varied. Bike thieves can be either opportunistic, only bothering with easy targets like completely unsecured bikes, or they can be determined, waiting until a bike is unattended before trying to bypass locks. Another aspect of bike thieves is how well-equipped they are. Bolt cutters and bottle jacks are commonly used to break bike locks. Typically, more determined thieves will be better equipped.

Because bikes are assembled from several separate parts, it is common for thieves to steal as much of the bike as they can. If a lock only secures the wheel of a bike, a thief can detach the wheel and steal the rest of the bike:

A partially stolen bike. The cyclist failed to secure the frame of the bike to the rack.

A common feature of many bikes is detachable wheels and seats that can be removed without tools, making these components easy targets for thieves. If a thief seeks to steal a whole bike, they will typically try to break the lock securing it. As mentioned earlier, bolt cutters and bottle jacks can be used to break locks. In addition, the lock mechanism itself can be targeted. Depending on the manufacturer and model of the lock, it may be more vulnerable to lockpicking attempts.

Another vulnerability of bike locks is that the most commonly used types rely on some sort of fixed object (such as a bike rack) to lock the bike to. This reliance can be exploited by thieves who use what is called a “sucker pole.” A sucker pole is simply an object that appears to be fixed to the ground but can actually be detached and lifted.

A bike attached to a sucker pole. Note the missing bolt on the pole that would keep it fixed to the sidewalk.

One more potential attack involves the deliberate misuse of bike locks. Suppose a thief sees a bike locked in a secluded area. The thief goes to the bike and attaches their own bike lock to the already locked bike. This additional lock prevents the owner of the bike from taking their bike with them. The thief can then wait for the person to have to leave the area and proceed to break the first lock with tools.


As mentioned previously, there are various types of bike locks for preventing various types of theft. The most common and secure is the U-lock or D-lock. It works by locking the bike to a fixed object and requires a key or combination to open. These locks are usually considered to be the most secure and resistant to attacks, provided that the bike frame and wheels are properly secured. Thieves will typically attempt partial theft on bikes secured with U-locks as it is somewhat difficult to lock down every part of the bike with one U-lock. The only truly reliable way to break a U-lock is with a bottle jack, which only especially well-equipped thieves will carry.

A typical U-lock.

Cable and chain locks work the same way, by locking the bike to a fixed object. They consist of some sort of long, durable material that is connected by lock that can open to a combination or key. These locks are considered to be not as secure as U-locks because they can be easily broken with bolt cutters. They do however make it easier to secure more parts of the bike (e.g. frame and wheels) and as such are somewhat better for preventing partial theft.

A typical cable lock.

Other types of locks are intended to prevent only opportunistic theft. Wheel locks, as their name implies, lock the wheels of a bike so that they cannot roll. Thus, thieves trying to steal the bike will have to carry it instead of being able to roll it or ride it away. The added security is somewhat limited but it is sometimes enough to deter casual thieves.

A wheel lock.

Locking skewers are another defense against casual thieves. As mentioned previously, many bikes come with detachable seats and wheels that can be removed without tools. Locking skewers replace these locks and secure the parts so that they can only be removed with tools. Thus, thieves cannot easily detach parts of the bike.

A locking skewer applied to a bike wheel.

Possible Improvements

One possible improvement would be bikes that have locks built into them. These built-in locks could be used in conjunction with separate locks to improve security. This set-up would provide additional security with no added portability cost to the user. For example, the bike could include locks to secure the wheels to the frame, and then the cyclist could use a U-lock to attach the bike to a bike rack.

Another possible improvement to combat sucker poles would be some sort of system by which cyclists could identify safe-to-use bike racks. This could be as simple as a hard-to-replicate seal on the rack itself, or even a map of locations of safe bike racks that could be provided by the government. Such a system would be implemented locally. It would only be worth the added cost if sucker pole bike theft is a serious problem in that particular location.

Holistic Evaluation

Bike security is inherently a tough problem. The objective is for the cyclist to be able to leave their bike outside, in public, in a variety of locations, and prevent it from being stolen. Leaving anything unattended in public for an extended period of time is inherently risky, and as such bike security is never completely assured (but then again, no security is!). Locking the bike to a fixed object is the most low-maintenance and cost-effective way of achieving this aim (imagine having to hire a bike bodyguard). In this sense, bike security is fairly well developed, with bike racks being common public objects and cyclists having a wide variety of locks to choose from.

Cyclist education is an integral part of bike security. Many forms of theft can be prevented if the owner of the bike is aware of potential risks. For example, when purchasing the bike, if the cyclist knows that the seat and wheels are detachable, then they will likely not leave the bike unattended for long, or they may invest in locking skewers. Partial theft can be prevented by proper use of locks, ensuring that all detachable parts are locked down. Some bikes may require multiple locks to be properly secured. Sucker poles can be made ineffective by teaching cyclists what to look for, such as missing bolts at the bottom of the pole.

Overall, bike security is a well-developed system that provides cyclists with the ability to leave their bikes unattended in public spaces. Thieves employ a wide variety of techniques to circumvent bike locks, but cyclist education is often enough to prevent such theft from occurring. The risk of leaving anything in a public space is obvious, but the technology and infrastructure of the system make it fairly reliable and enough for most people.

Sources (general info on types of bike locks) (info on sucker poles)