U-Locks U-Locks or "D-Locks" as the cool hipsters call them are a thick piece of steel shaped like the letter U or D. U Locks are one of the most popular locks available because of its ease to use and their high level of security. U-Locks are perfect securing your bike to the Bike Rack, Flag Pole or Parking meter.
U-Locks are the ubiquitous and silent partners we all know and use to keep our bikes safe. But, unlike chains and cables, which have been around since the beginning of the bicycle, U-locks came on the scene relatively late, around 1970. That's when a bike mechanic in Cambridge Massachusetts, Stephen Kaplan, started fashioning U shaped locks from iron. Kaplan's invention was noticed by Michael Zane who saw mass potential in the invention. Together they started Kryptonite Locks and the rest is history.
Today's U-locks are made by various manufacturers, including Kryptonite, which still makes some of the best. Materials have improved dramatically from the old iron locks. Shackles have become fatter, key and combo mechanisms more attack resistant, and high end locks offer forms of insurance/reimbursement/registration, should your trusty steed be rustled.
The best U-locks offer significant protection in a world where no lock can't be defeated with the right tools, time and knowledge. Prices can vary, too, from economical to pretty expensive. If you want the best, it's gonna cost ya. And, there may be a point of diminishing returns once you've gotten to about the middle of the pricing spectrum. Still, if you want more tumblers, butter silk locking mechanism and a bit less weight, it may be worth it to you. Just remember, a U-lock can't do it all. And, generally, the smaller the U-lock the less vulnerable it is to leverage attacks. So, smaller U-locks and chains/cable combos are very popular.
A dedicated knowledgeable thief with time, tools and opportunity can defeat any lock. Keep that in mind. Learn how to use your U-lock correctly. Hopefully, a thief will look elsewhere for a target. U-Locks are can be used on any bike and in any situation. However, due to their weight and sometimes size they are best used when your bike is exposed to high traffic/urban areas where you need additional security or you have a high dollar ride you need to secure. If you're riding your daily beater around town, it may be easier to carry a cable or chain lock which in most cases offer plenty of security for lower end bikes.
Most U-locks are keyed, but you may be able to find a combination U-lock... this being said, the ultimate in security will always be keyed over combo. A crafty bike thief can usually figure out a combo lock just through feel of the numbers. Barrel locks are all but gone on U-Locks, look for a lock with flat key (these offer greater security).
Keep in mind most bikes are not stolen due to cheap locks, they are taken because they are not locked properly. No matter which lock you choose make sure at a minimum your frame is locked securely and attached to an immovable object. If your bike is attached to something that can be moved or easily removed the security level or type of lock you have does not matter.
Cable Locks There's some great things about cable locks. They're usually lighter, come in a variety of cable lengths, width, lock types, and are easier to use. These are all great qualities. On the other hand, the usage profile for cable locks is generally in a lower threat environment. And, cable locks lend themselves for use in conjunction with other more difficult to attack locking strategies like U-Locks and chains.
Chain Locks When you need the uber-security of a U-Lock, but the useability of a cable lock, there is just no beating a heavy duty chain lock. Chain locks can vary from worthless hardware store chains all the way to tool hardened steel with special features to deter cutting. Pair a hardened chain with a U-Lock and you have yourself a security solution worthy of the toughest neighborhoods.
The question really is, do you need a chain lock with its weight, mass and inconvenience of use? Chains lend themselves to securing longer bikes, like long tale cargo haulers, electric bikes with expensive hubs, and anytime you want more security for your wheels than maybe a U-lock/cable combo.
The biggest problem with chain locks is that to be effective they must weigh a lot. They are definitely the heavyweights of the extended lock family. Some More expensive chain locks are designed specifically with links that resist attacks like leverage and cutting. The best have small U-locks to secure the ends of the chain that are also designed to withstand cutting and leverage attacks. They can weigh upwards of 15lbs, too. But, experts agree: all locks can be cut and opened, but the best chain/U-lock systems are about the most secure.
When looking for a chain lock, think about where you're going to park your bike and how long you're going to leave it unattended. Again, remember, the best thieves with the right tools and time can defeat any lock. The idea is to make your bike look less appealing to steal. If you have to leave your bike in an out of the way or secluded place for an extended period of time, you may have no choice but to utilize a more expensive chain lock to hopefully minimize possibility of theft.
Bicycle thieves usually come in two varieties, opportunists and professionals. Opportunists will look for the easy victim and will usually be not as well equipped. The professional may even case your ride and be looking for certain bikes or components. Professionals are probably going to get your bike if they target it and they have the opportunity -- no matter how you lock it.
Folding Locks The folding bike lock combines the security of a U-Lock with the portability of a cable lock. Bringing together all the best features of both and ensuring that your bike will be around when you return. Folding locks resemble a folding carpenters ruler and functions in a similar manner. Allowing for easy transport and numerous locking options.
In use, folding locks easily articulate through frame members and wheels, not to mention around bike racks, sign posts and small trees. The series of plates move freely and on only one dimensional plane, making them less of a wrestling match to use than coiled cable locks which spring back. It takes a bit of initial trial-and-error to learn the multi-link ropes, but once you do it becomes an easy scenario to manage. The thin plates also allow for you to easily secure your helmet through one of the vents as well.
Carrying a lock is always an annoyance, but most folders make transport a breeze. The lock fits in an included hard rubber holster which secures to the frame via hook-and-loop straps or by bolting it to water bottle bosses. Both methods result in blissfully, rattle-free transport. Also keeping your lock attached to your bike means you won't forget it when you need it.
Folding locks, due to the hardened steel articulating plates are notably immune to the more likely scenario of bolt cutters which are portable, silent and quite effective on cable locks. In most instances, locking your bike with any folding locks in a conspicuous place would prompt most would-be thieves to move along to easier pickings.
Folding locks are perfect for daily commuters and students that need easy transport and medium security. If you plan on leaving a higher end bike outside for extended periods a smaller U-Lock is probably your best bet. Keep in mind that no lock is immune to a motivated thief!
Speciality Locks Not your typical day to day bike locks. These locks are usually found in Europe where bike commuting is more of a culture and bike theft is not as prevalent as here in the States. By no means should this imply these locks don't work but rather they are not what we are used to seeing.
Seat post mount locks are super cool and remain mounted to your frame, so you will always have a means of securing your bike. Since these locks attach to your rear wheel they make it impossible to ride your bike when then are locked. Kind of like the boots police departments use to lock car wheels. Seat post mount locks are easy to use, effective and convenient. They are perfect for daily commuter that makes quick stops to and from work.
Although your bike is only locked to itself, seat tube locks are a nice determinant for grab and go thieves. For extend stays I would recommend getting the Trelock 140CM Plug in Chain for RS445 which allow you to attached your bike to an immovable object that further secure your ride.
We have locks for your bike and to protect your bags and bike components as well. Bike commuting or touring, having a solid lock to secure your bike and your bags and components will give you peace of mind. Cover your bags entirely with the PacSafe 120 to help keep you at ease when you have to leave your gear. The stainless steel mesh covers many different sized bags, and can cinch to the size of your cargo for extra tight safety. Or lock your panniers down with the Ortlieb Pannier Security cables... these Security Cables attach to the top rail of the panniers. The loop on the end of the Security Cable allows for cable locks as well as U-locks to be fed through thus locking the panniers to the bike. Or Pinhead locks to secure you your entire bike.