How to Choose a Great (And Not so Great) Bike Lock

When I bought a fancy bike last year, I felt I needed to upgrade my security for it. Holy cow, is there ever a swamp of options to wade through when choosing a bike lock. Cable locks. U-locks. Chains. Kryptonite. Onguard. Blackburn. Abus. And they’re all so different.

After many hours of research, I picked a very secure lock. Then immediately had buyer’s remorse. I wish someone had told me to consider weight and convenience. My purchase, a Kryptonite U-lock, model “New York Lock M-18WL,” for $120.  While very secure, at 6.5 lbs it’s a total pain to carry around. After a few months, I got tired of schlepping that monster everywhere and had to find another, lighter-weight lock.

Back to the drawing board!

Two basic design principles had originally led me to buy the New York Lock M-18: a narrow shackle and 16mm thickness (or greater). These two design features neuter the two most common attacks against U-locks.

1) Bottle jacks: Bike thieves can bust open nearly any U-lock using a twenty-dollar tool available at any hardware store called a bottle jack, as demonstrated in this video . . . (Darn, YouTube has taken down all videos of bottle jacks defeating U-locks.) That is, unless the shackle is too narrow to fit a bottle jack inside the “U”.  If the jack won’t fit, it’s useless against the lock. Here’s a photo of a bottle jack beginning to warp a U-lock shackle: (photo credit needed)

2) Bolt cutters: A shackle with a thickness of 16mm is too thick for the jaws of even the largest bolt cutters. Less than 16 mm can easily be cut by bolt cutters, like this:

The little brother of my New York Lock M-18, called the New York Fahgettaboudit Mini ($90), has both a narrow shackle and an 18mm thickness. And it’s lighter and smaller; its shackle is only 4 inches long, instead of 8 inches, making the NYF Mini only 4.55 pounds. I could have saved myself more research by just going with it. http://www.kryptonitelock.com/Pages/ProductInformation.aspx?PNumber=997986     

But that’s still heavy. Worse, an even bigger problem is its shackle is actually too small to be practical. It’s so small, people ride around with the NYF Mini stuffed in their back pockets. For portability, that’s a pretty great feature. However, the shackle is so narrow, it severely limits the ways in which one can lock up a bike. It can lock a bike frame to a bike rack, but without room for either of the wheels. Plus, if your frame tubing is oversized, as mine is, good luck using the NYF Mini on a thicker street pole (like a parking meter). It just won’t work. And the lock is too small to lock up just the rear wheel, as shown below with a larger lock: (photo credit needed)

The Sweet Spot

I eventually found a U-lock by OnGuard, the Brute Mini ($70), which hits the sweet spot between strength and weight. At 16.8mm thickness, the Brute Mini is impervious to bolt cutter attack. Yet the lock weighs in at a svelte 3 lbs. The shackle is also about 15% larger than the NYF Mini. With just that much additional size, I rarely have difficulty locking up my bike. Yet the shackle is still too small to fit a bottle jack.  (See my photo at the top of this post. There’s no way to fit a bottle jack inside the shackle.)  http://onguardlock.com/products/u-locks/brute-mini-u-lock/

Bike Locks I Ruled Out

Lots of people use cable locks because they’re cheap and convenient. They’re lightweight and easy to stow. But against bolt cutters, they get snipped like ribbons.  “Steel-jacketed” cable locks are a little better because they’re fatter. But they’re better only to the extent that a thief would need a second tool to get through it: one tool to flatten or saw through the (very thin) outer steel jacket, and bolt cutters for the inner cable. See the outer jacket separated from its inner cable, below. (Photo credit:  http://lettershometoyou.wordpress.com/ )

Case-hardened hex link chain might seem like a solid option, especially since it is marketed to motorcycle owners. But the thickest hex chain is only 14mm. Thus, a pair of 42-in. bolt cutters can quickly dispense with even a $150 chain, as seen here:

Plus, a three-foot length of 14mm hex chain will run about 10 pounds. And that’s not including the lock! There is a security chain manufacturer in the UK called Almax, which produces thicker, non-hex links. But, again, the weight. Such beasts were never meant to be carried on a bicycle. Maybe for locking up at home, but certainly not to carry on one’s daily commute.

In my research I came across the very cool TiGr Lock. Sadly, I found it just after its Kickstarter campaign had expired. Doh! Missed my chance to get one for $100. Now that they’re on the market, the 0.75-in. version is $165, and the 1.25-in. version is $220. http://tigrlock.com/ Wired Magazine reviewed the TiGr Lock as “deliver[ing] the holy grail of locks–strength and lightness…” The 1.25-in version is immune to bolt cutters, and weighs a mere 1.5 lbs. Be still my heart.

But I’m just not able to plunk down $220 for a bike lock. Maybe if I hadn’t already squandered so much on that $120 albatross, the New York Lock M-18.  Sigh.

(UPDATE: I spoke too soon in praising the TiGr Lock. Have a look at this video:

Granted, the TiGr Lock being cut in the video is the 0.75-in. model. But the bolt cutters snip that lock so easily, it’s hard to believe the wider version would make much difference. (The 1.25-in. model is wider, not thicker.)

Two Attacks NOT to Worry About

Ever heard of the liquid nitrogen attack? In bike thievery lore, a lock can be shattered if frozen with liquid nitrogen, then hit with a hammer. In the wild, liquid nitrogen is simply not a common threat. Here’s a discussion of it: http://www.creekcats.com/pnprice/bikelock.html

Also rare is the angle grinder attack. The first time I saw an angle grinder in action, my heart sank. An angle grinder can dispense with any lock listed here in 90 seconds, quicker with any lesser lock. Much quicker. The good news is they cause a scene. They throw a shower of sparks and shriek like a banshee:  https://www.youtube.com/watch?v=bphyY1pnjg8  To guard against an angle grinder attack, one simply needs to park one’s bike where 90 seconds of sparks and screeching noise would be unwise for the thief. (Photo credit needed.)

Final Notes

No matter what type of lock you use, there’s one security principle that undergirds all scenarios:  how long you leave your bike unattended. The longer a bike sits in one spot, the higher the chances it will catch the eye of a bike thief. Also, knowledge that the owner won’t return anytime soon puts the bike thief at ease. That’s the worst kind of bike thief: the brazen thief, the confident thief. Even if your bike is secured well, given unlimited time, bike thieves will take what they can. (Photo:  Luca Masters)