There's a maxim running 'round the Internet about bikes and locks: All bicycles weigh 50 pounds. A 30-pound bicycle needs a 20-pound lock. A 40-pound bicycle needs a 10-pound lock. A 50-pound bicycle doesn't need a lock at all.

There's some truth to it. The fact is, any bike lock can be broken with enough time and firepower. A bike thief can buy a rechargeable angle grinder and battery for less than $100 and it will go through almost any lock like butter. It has been demonstrated many times (particularly wonderfully in the video below by Casey Neistat) that nobody is going to run up and stop them. As noted in TreeHugger, it's a low-risk gig for a thief:

While a stolen bike probably isn't that valuable, what matters is that in most places, there's basically no chances that you will be caught. While thieves aren't always the most rational people, they are rational enough to know that a low-paying risk-free crime can pay a lot if you do it enough times to compensate for the low value of each stolen booty.

The point of the bike lock is to a) make your bike the least attractive target, b) scare off the amateurs, and c) slow down the professionals. So here's the drill:

1. Use a bike lock — all the time.

Your bike can be gone in a flash, yet so many people just run into stores for a second without doing it and find their bike gone when they come out — and their expensive lock gone with it. 

2. Lock it to something solid. 

A proper bike rack is best. Locking it to a tree is not a good idea; it's not good for the trees and it doesn't provide a whole lot of protection. There is even a famous video of thieves using an axe to cut down a hefty ginko in New York to steal a cheap department store bike.

3. Lock it to something legal.

Often bikes will be removed by security or building managers if you lock to handrails, particularly if they are near wheelchair ramps or just because they are jerks. 

4. Spend as much as you can afford for your lock

The heavier and clunkier the lock, the harder they are to cut through. Unfortunately, that bulk also means more weight you'll have to carry while you cycle. 

5. U-locks, also known as D-locks or shackles, are still considered the most secure.

That's the word from insurance companies and police departments. However there are different qualities, sizes and permutations in the world of U-locks. In terms of size, small is the new big; the more tightly the lock holds the bike close to what it's being locked to, the less chance there is of banging it back and forth or getting a crowbar or 2x4 in between. Use what's known as the "Sheldon technique":

People tend to buy the big clunky U-locks because they don't know how to use them properly. A U-lock should go around the rear rim and tire, somewhere inside the rear triangle of the frame. There is no need to loop it around the seat tube as well, because the wheel cannot be pulled through the rear triangle.

This is how it's done: Uglified dirty bike with small lock, using Sheldon Technique. (Photo: Lloyd Alter)

I personally use a mini Abus U-lock and the Sheldon technique as shown above. Yvonne Bambrick, author of the Urban Cycling Guide, recommends locking through the frame and the rear wheel, with a cable going through the front wheel, as shown below. It takes a bigger lock to do this.

In Europe, all U-locks are tested with a Sold Secure rating; insurance companies insist that you have a lock rated appropriately for the value of your bike. The higher the rating, the heavier (and more expensive) the lock. Many higher-end locks come with insurance policies and will replace your bike if the lock is busted, and registries that can replace your key if you send them the serial number.


Really you don't need to be a hipster. (Photo: Hiplok)

6. Chain locks are solid but heavy.

Yvonne Bambrick writes: "I love my thick, cloth-covered Abus chain: It's super-strong and gives me the flexibility to lock more than just typical bike parking, often designed with U-locks in mind." But they can be heavy; In his review, Eric Hansen writes: "Chains sometimes offer a slight bump in security, but they often weigh twice as much and still relent to power tools. Let masochists wear belts of hardened steel." In fact, they are a bit of a fashion statement; the new Hiplok is actually designed to be worn comfortably around your waist. They are not just for tattooed hipsters, really.

7. Cable locks are getting better.

But they are still not as good as U-locks and the cheap thin versions are "like locking your house with a screen door," according to the Urban Cycling Survival Guide.

8. Neat new innovations in bike locks

skylock bike lock

Lock your bike to the internet of things (Photo: Skylock)

In this era of the Internet of Things and Mesh Cities, it's not surprising that there are now smart Internet-connected locks that you operate with your smartphone. Superficially it sounds like one of those dumb ideas, but these locks have some interesting features. For example the new Skylock not only unlocks with your smartphone instead of your key, but it has "a triaxial accelerometer to detect tampering conditions." If someone tries to steal your bike, it sends a message to the cloud servers and notifies you. If you hit something, it will ask you if you are OK, and if you do not respond it will call for help. 

litelok fabric bike lock

Five minutes of protection. Guaranteed. (Photo: Litelok)

Also very interesting is the Litelok, which is made with a combination of different materials and layers, each designed to defeat different tools that either slip, bounce or stick. As noted before, no lock is unbreakable, and even this one only claims that "in-house testing has proven that it takes well over five minutes to cut or break the strap and lock."

9. Other things you can do to keep your bike safe

Since it's clear that no bike lock — no matter how fancy or expensive — is unbreakable, there are other things you can do to make it harder for the thieves. Those things include:

  • Always park in a public place. Even though we know that people ignore bike thieves, it still makes life easier for them if you are parked in some quiet, out-of -the-way spot.
  • Use more than one lock if you can. It just slows them down a bit more and means that they'll need more tools.
  • Consider uglifying your bike. Seriously. If it has a lousy paint job and looks like junk, it might be ignored.
  • Make them work for it. As Bike Radar notes: Make the lock mechanism hard to get to; if it’s a pain for you to unlock it, it’s a pain for a thief to get at, and being a lazy bunch, they’ll move on.
  • And just in case: photograph your bike, get all the serial numbers, and if your city has a registry, get your bike listed on it. Then you might have a chance of recovering it. 

Lloyd Alter ( @lloydalter ) writes about smart (and dumb) tech with a side of design and a dash of boomer angst.