An absolute necessity for any cyclist living in a major metropolitan area who wishes to leave their bike unattended for any length of time, a U-Lock is a wonderful invention with a solid, efficient design that serves so many utilitarian purposes, it's almost as versatile as a Swiss Army knife, and stands up to punishment better than a rusty old chain.

Named, obviously, for it's U-shaped appearance, the primary function of the lock is to secure a bike frame around some stationary object, like a parking meter, or a stop sign post, or a fence, or a rack of some sort, or another bike frame already shackled to some poor object that has a dozen other cycles attached to it (a common scenario found outside college buildings). The U-shaped portion is a solid curve of about a half-inch of reinforced steel, which is purchasable in varying lengths from four inches to nearly a foot. A locking bar with a circular key lock crosses the tips of the U to complete the circuit of metal. The whole thing is laminated with a waterproof synthetic coating, which also aids in keeping a grip on the thing when using it for a more offensive purpose.

Commonly, the best way to lock a bike down is to loop the U-lock through the end of the front tire and upwards through the lower bar of the forward portion of the frame (also known as the 'down tube'), while simultaneously embracing with it whatever immovable, un-fuck-withable object you're securing it to. This prevents someone from making off with your front tire, and the rear tire is regarded as fairly safe unsecured, as it tends to be a hassle to remove in general, given the complex tangle that the derailleur system makes around the rear hub, compounded with the difficulty involved in lifting the rear section of a properly-secured bike off the ground to allow the thefted tire to be rolled out. Some riders take the rear tire off themselves, and integrate it with everything else secured up front.

Now, while the u-lock will do well in deterring a theft, it cannot absolutely stop people from fucking around with your ride. Firstly, all the hype on the box about it being "bolt cutter and leverage-attack resistant" is true enough to stop the amateur criminal, but any professional in the industry will gladly inform you that if the consummate bicycle thief wants your cycle badly enough, he'll get it. That's why it's good to make your bike look as unattractive as possible by never washing non-mechanical areas, covering it with stickers and tape, and locking it next to prettier, cleaner, more expensive-looking bikes. Picture, for example, the mildly attractive person who takes a less attractive 'friend' of the same sex out clubbing for the purpose of, through comparison, enhancing their own beauty. Let your bike be that ugly friend; you do not want it to be slipped GHB and date raped at the end of the night. A braided-steel cable also helps, as it can be looped through various detachable components such as quick-release seats, suspension systems, lights, that rear tire and soforth. As for physical vandalism; there's really no way to keep your bike entirely safe from tire slashing, spoke smashing, cable cutting, brake tampering or any other imaginable form of abuse; your best bet is to just keep your frame rather low-key, and put anything controversial (stickers indicating stances on abortion, politics, etc.) which may piss someone off on some other object.

As for the secondary use of a U-lock, one only needs to pick up the thing and heft it around for awhile to realize that it can do a hell of a lot of damage if swung properly (hand clasped around the dip of the U, the upper lock-bar used as the impact surface). A good smack from a U-lock can knock the teeth out of human assailants and the windows out of vehicular ones; it isn't unheard of for bike messengers to use their locks to put dents in the hoods of aggressive taxis and SUV's after near-collisions, regardless of fault. Best kept dangling off the handlebars for easy access, a rider can often find that merely raising it in the air or waving it about menacingly will clearly establish and fortify your legal right (in America and the UK, as I'm aware, and most positively elsewhere in this world) to the full usage of a traffic lane in the minds of any obstinate, honking drivers.

U-Lock Security

And security problems...

U-Locks are physically one of the safest ways to lock up anything. Name brand varieties (Kryptonite, for example) are made from hardened steel, and as such are quite resistant to filing or sawing. I can say from personal experience that trying to use a propane-oxygen torch on a hardened U-Lock is also not very productive, as the cutting process can take upwards of 45 minutes--plenty of time for someone to pass by and notice a thief trying to steal your bike. Many thieves try using car jacks to break the locks, and though this can be effective, it is very conspicuous. The bolt itself is also well designed. Though it often varies by company, it is usually some variety of a catch that fits over a notch on one of the legs of the U. Most Kryptonite locks use a curved steel bolt that rotates over the notch on the bar. This is obviously very hard to tamper with, making it difficult for someone to use brute force to break the lock and steal the bike.

For years, these traits served to make U-Locks the ultimate mechanism for securing thing such as bicycles, barbecue grills, and gates. However, there is one element of U-Locks that makes them almost worthless: the lock itself. U-Locks have for decades used "tublar cylinder" locks (the type with the round key). Many people thought these were safer than the traditional flat key lock, since it would be harder to pick them. This is in fact true; picking a circular lock is difficult. Most have seven pins, set at different depths, and requiring different levels of depression. And, unlike a traditional lock where after setting the pins, all one needs to do is turn the cylinder with some flat object, a tubular lock requires that the pins themselves be moved in a circle, making "traditional" lock-picking quite difficult.

However, tubular cylinder locks are very vulnerable to a technique known as raking. Racking is simply forcing some object into the lock and physically turning the lock's cylinder, so that the pins are forced into position without you actually going through the trouble of trying to set them. Because a tubular lock lacks the grooves common on flat key locks, all one needs to defeat a tubular cylinder lock is a round, reasonably sturdy object the same diameter as the key. For Kryptonite locks, a plastic pen cartridge will usually do the trick. Older models had slightly wider keys, so while a Bic pen will not work on them, the cap off of a thin Crayola marker fits perfectly. To open your tubular lock, simply force the pen cartridge or marker cap in as far as possible--you may need to tap it a bit--treating it as if it itself were the key. Full insertion is important, because if you don't depress the pins at the bottom, the lock will not turn, and all you'll do is tear up whatever you're using to force the lock. However, if you succeed in depressing all the pins (it's not that hard, especially with practice), the next step is simply to turn your marker cap or pen, and the cylinder itself will follow just as easily as it would if you were using a key. After opening your lock, remember to turn the pen/marker cap back to its starting point, or else you won't be able to fit a key in the lock, as the cylinder will still be turned to the unlocked position. Some people on online forums noted that if you turn the lock the full 180°, you may not be able to return it to the locked position with the pen/cap, so be careful when trying this out.

Though this technique has been known for some time (the UK magazine New Cyclist had an article in 1992 detailing this method), it wasn't until late September 2004 that it became publicized, thanks in great part to the internet. The results, of course, were not at all good for lock-makers. Kryptonite, because it was well-known, got most of the bad press, and has voluntarily decided to run an exchange program (details below). However, a Kryptonite U-Lock is not the only thing vulnerable. Any device with a tubular cylinder lock is at risk. This includes anything from U-Locks by other manufacturers to the key switches on some home security systems to the locks placed on many soda vending machines. Though it is probably possible to modify the cylindrical lock's design to make it impervious to office supplies, the only available solution currently is to replace the cylindrical lock with a traditional flat key lock.

Recall Information:

Kryptonite has decided to voluntarily recall and exchange many of its lock models. Details are available on their web site (, which also includes a convenient form. Kryptonite will pay postage; the customer need only provide their name, address, lock model(s) and key number(s).


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