How to Choose the Right Bike Lock

How to lock your bike really securely. (Photo: Dustin Quasar/flickr).

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.