For the previous version of this guide, we researched the different rating systems from foundations such as ART and Sold Secure, and we spoke to professional bicycle thieves.

But it was hard to make an apples-to-apples comparison, since all the rating systems are independent of one another. We scoured the Web for every lock review we could, but no single review had tested as many locks in as many ways as we hoped to do, so we knew it would be difficult to make any comparative judgments unless we tested the locks ourselves.

So from our experiences working in shops over the years and interviewing thieves themselves, we created a list of the most common tools that bicycle thieves use to defeat bike locks. It became the checklist that our group of locks would need to survive in order to become a pick.

The tools

Lock picks: These are the smallest, quietest, and most portable tools to carry, but they also require the most skill to use. Different locks require assorted tools and pose varying degrees of difficulty to pick; however, once a thief has the tools and the proficiency to quickly open a particular lock, it merely becomes a matter of walking the streets and looking through racks of bikes for a target lock they recognize as being easy to open.

Cable cutters: Thieves carry out a large number of bike thefts (possibly most of them) using a simple pair of diagonal wire cutters. These tools are easy to carry in a pocket, quiet, and simple to shoplift if not owned already. Unfortunately, the only reason simple diagonal cutters are so effective is because people continue to lock their bicycles using only a braided steel cable and a padlock or a basic cable lock, even though such devices should be used only as accessory locks in most situations. A good set of bypass cutters can cut these locks in a single pass, and a tiny set of diagonal cutters can do so with multiple snips.

Hacksaw: A hacksaw can be quiet and can work through a nonhardened lock quickly. Most chains from the hardware store, cheap U-locks, and cable locks can be defeated with a hacksaw. The main drawback is that a hacksaw can be slow on a thicker lock, may catch and bind while trying to cut through a cable, and takes some physical effort to use in general. It is a very cheap tool to come by, though, and an easy one to carry and conceal.

Bolt cutters: From my experience working in shops over the years, I’ve heard hundreds of stories of stolen bikes and seen many cut locks, and most of them (not including snipped cable locks) have been cut with bolt cutters. Bolt cutters can be quite small, usually 18 to 24 inches long. They’re quick to cut through a lock, cheap, portable, and easy to conceal. They don’t work on every lock, but for the ones they do work on, it’s only a quick snip and a free bike.

Cordless drill: This is a rarer tool for bike thieves, as it works well on only a few types of locks, and most of those are also easier to defeat using other methods, but occasionally drills do see use (most often during an attempt to drill out a lock’s core). The locks that drills do work well on (such as folding locks) have become more popular, though, and the reduction in noise and size over an angle grinder makes a drill a tempting tool for a thief to carry.

Angle grinder: A thief with a battery-powered angle grinder will defeat any lock if given enough time. For the thief, the biggest con to the grinder is the noise and sparks it emits as it grinds through hardened steel. In the past, cordless tools didn’t have the power for such uses, but battery technology has advanced enough that they can perform just as well as their corded counterparts, and thus they have changed the landscape of bicycle security. It’s hard not to notice one of these tools, but a thief who can mask the noise and is brazen enough to use one will probably be successful in stealing the bike.

We did not pry open any locks with car jacks, because the jack has to fit inside the shackle. That kind of attack can be made more difficult by using good locking technique, which means choosing a lock size that leaves very little room inside the shackle to fit a tool.

After we had our list, we needed to decide how the results of the tests would allow us to rank the locks. We believe that any form of security is only as good as its weakest part—think of a locked house with an open window, for instance, or an operating system with a backdoor. So we decided that the more quietly and quickly a lock could be opened, regardless of how well it performed in other areas, the lower it would score.

The first test would be to see if any of the locks could be picked (some could); to see if any fell victim to bolt cutters (some did), hacksawing (sadly), or drilling (no problem); and finally to see how long each would take to cut through with an inexpensive portable angle grinder (quicker than you might think). After we completed all the tests, we ranked the locks based on their security and price to see where they stood, and then we factored in features such as durability, weight, portability, and ease of use.

The testing methods

Lock picking

We contacted John Edgar Park, an avid lock-picking enthusiast and instructor with over 20 years of experience, and we sat down together to review all the locks we had received. With a quick visual inspection and a few pokes from one of the many pointy tools he had brought along in a folding leather pouch, Park immediately singled out how each mechanism worked and the easiest way to defeat each lock. He also taught me how to pick a lock, which I managed to do to one model in less than 30 seconds. It’s a simple raking technique that requires little skill and basic tools; someone could do it with a couple of pieces of scrap metal from a car’s wiper blade or a pair of bobby pins. And I had always thought MacGyver was a joke!

Just to be sure, we also got in touch with a lock-picking group, and we visited on a night with a presentation on disc-detainer locks, a type of high-security mechanism used in some bike locks. The meeting was in an unmarked building in an unmarked room, and among the many interesting things we found out was that even the more basic disc-detainer locks we brought were very hard to pick, and nobody at the meeting had the proper tools to fit the smaller keyways most bicycle locks use. As a result, we’re confident that disc-detainer styles are secure against most lock-picking thieves.

Bolt cutters

The next test: bolt cutters. These tools are available at any home improvement store and usually make a sound during a theft only after it’s too late, when the lock splits apart and the thief is off with your bike. You could be within 20 feet of your bike and still not hear it. For our tests we used cutters of two lengths, a 24-inch HDX pair from Home Depot and a 36-inch Tekton 3421.

Some of the locks we tested claimed to be resistant, but most of them fell to our bolt cutters eventually. The easiest U-locks to cut through appeared to be only case hardened, which seems to do little to stop bolt cutters, since the tool’s jaws can crush and split the softer metal underneath the hardened shell. More expensive locks will be hardened more thoroughly, via a different heat-treating process.

As described in an email from Mark Podob of Metlab, a heat-treating company: “The advantage of case hardening over through hardening is that it provides a hard surface to a certain depth and allows for the use of a less expensive low carbon steel for the ‘U’ material. On the other hand, once the case is penetrated, sawing through the rest of the material can go quickly.”

Despite the hardened outer shell on these U-locks, our smaller bolt cutters were still able to crush the softer inner metal. Photo: Duncan Niederlitz

A few examples of the cuts left behind when we used bolt cutters. Photo: Duncan Niederlitz

Despite the hardened outer shell on these U-locks, our smaller bolt cutters were still able to crush the softer inner metal. Photo: Duncan Niederlitz

A few examples of the cuts left behind when we used bolt cutters. Photo: Duncan Niederlitz 1 of 2

Hacksaw

We weren’t expecting notable results from the hacksaw test, as even modest case-hardened steel usually deters a hacksaw. However, the Altor and TiGr locks are both made of titanium, which is tough but not very hard, and the hacksaw proved that. With the hacksaw, we cut through each lock, held in a vise, in less than 30 seconds. Our using the vise probably resulted in a cut time quicker than that of most real-world scenarios, but practiced thieves have a few tricks (using zip ties or leaning against the bike to steady it) that make these times not too far off from what you could expect. The RockyMounts lock we tested uses stainless steel, a material rarely found in bicycle locks, which to our eyes appeared to be left unhardened; despite the lock’s large shackle diameter, our hacksaw cut through in just 90 seconds.

The TiGr Mini also proved vulnerable to the hacksaw and vise combo. Photo: Duncan Niederlitz

We were able to cut the RockyMounts Compton Large with a hacksaw when we held it in a vise. Photo: Duncan Niederlitz

We were able to do the same to the Altor 560G. Photo: Duncan Niederlitz

The TiGr Mini also proved vulnerable to the hacksaw and vise combo. Photo: Duncan Niederlitz

We were able to cut the RockyMounts Compton Large with a hacksaw when we held it in a vise. Photo: Duncan Niederlitz 1 of 3

Cordless drill

While a small cordless drill is louder than bolt cutters, it’s still barely noticeable over the sound of a busy street. Also, it’s easier to carry and doesn’t cause as much suspicion as a large set of cutters, and it’s much quieter than an angle grinder. The one we used in our testing was a 12 V Milwaukee Fuel, which is small enough to put into a jacket pocket. While the Altor 560G gave in to the bolt cutters and the ABUS Folding Lock Bordo Granit X-Plus did as well after much effort on our part, the drill easily defeated both. A quick look was all we needed to see that the hinge was probably the weakest component of each system, and we quickly removed them by drilling straight through.

The ABUS Folding Lock Bordo fared no better when we went after its hinges with the drill. Photo: Duncan Niederlitz

The Altor 560G, while compact and easy to carry, allowed us to compromise it easily with drills at its hinges. Photo: Duncan Niederlitz

The ABUS Folding Lock Bordo fared no better when we went after its hinges with the drill. Photo: Duncan Niederlitz

The Altor 560G, while compact and easy to carry, allowed us to compromise it easily with drills at its hinges. Photo: Duncan Niederlitz 1 of 2

Angle grinder

The only test left to do was with the angle grinder. We knew all the locks would fall to the 7,000 rpm of an aluminum oxide disc—we just weren’t sure how long it would take. After years of hearing anecdotes from customers, reading marketing literature, and removing the odd lock here and there, we expected to take more than a minute for us to make one cut.

We learned that no lock can resist for more than a minute against modern tools.

We charged all the batteries we had for our cordless grinder, made extra coffee, and mentally prepared for the hours of grinding that lay ahead of us. Then the first lock took 14 seconds to cut through. The next, 15. Some of them couldn’t survive past the 10-second mark; the thickest and strongest ones still resisted for only 30 seconds before we made one cut.

We learned that no lock can resist for more than a minute against modern tools, even if it was a chain or had a dual-locking shackle and needed two cuts for removal. Granted, we did all these tests under ideal circumstances in a vise to create an equal setting for all the locks, but after testing locks in more awkward and unrestrained positions and seeing only a marginal increase in time, we can say that our results aren’t too far off from what you can expect in the real world. Even if it’s painfully obvious that a bike is being stolen, it seems to barely cause any alarm or attract attention, as demonstrated in one of my favorite videos (from The New York Times, which is now the parent company of Wirecutter).

So why bother to lock a bike? It unfortunately comes down to beating the people around you—after all, you don’t need to outrun the bear, you just need to outrun the other person with you. If you can ride a less expensive bike and lock it up properly with a better lock in a safer location, you can remove the temptation for a thief to pick your bike over an easier target.