What’s a Good Length for a Bike Lock?

A good lock will keep your bike safe when you’re not around. Now let’s get a little more specific.


Many factors go into choosing a bicycle lock.

For example, you need to decide whether you want a cable lock, chain lock, or U-lock. Some bike locks have a key, others a combination lock. In recent years, smart locks with Bluetooth connectivity have also become popular.

Then, there’s the lock’s thickness. A thicker lock provides more security, but it’s also heavier and harder to transport. So many decisions! In all this, we often forget one important factor that can make or break a good lock: its length.

A good lock should be long enough to enclose a wheel, the frame, and the rack, pole, or fence you’re locking the bike to. It should have the right amount of slack so you don’t scratch the bike, but not so much that thieves can easily break it open.

Read on to find out how to pick—pun intended—the best size bike lock for you.

How Long Should a Bike Lock Be?

So how long should a bike lock be, exactly?

The long answer short is that it depends on the bike, the rack, and how you lock your bike.

The good news is that you don’t have to guess if you don’t know what that ideal length is yet. You just have to know how to measure it, and what to measure it with.

Get a soft tape measure or a long piece of string, thread, or yarn; anything you can use to measure the length with. Then get on your bike and go to the rack where you will lock it the most. Set up your bike and measure how long the lock needs to be to fit around a wheel, the frame, and the rack.

Which wheel you need to measure depends on whether you want to lock your bike in the front or in the back with this lock.

Related: Which Bike Tire Should You Lock?

Add 2-4 in (5-10 cm) to account for the thickness of the lock and any accessories you have on your bike now, or will mount on it in the future. This, more or less, is your bike lock’s ideal length.

Does It Matter What Kind of Bicycle Lock You Get?

The type of lock you buy for your bike—especially if you park it in areas with high theft—can make the difference between finding it exactly where you left it and having to walk home because it was stolen.

Avoid cable locks at all cost. They give a false sense of security; an average thief can cut them with standard bolt cutters in a matter of seconds. The only good use I can think of for a cable lock is to secure an expensive bike seat to the frame.

With their hard steel and locking mechanisms, U-locks are considered by many to be the most secure type of lock on the market (Rolling Stone). But their strength is also their greatest weakness: because they are so hard and rigid, U-locks are the least versatile type of bicycle lock of all.

If your usual bike rack is occupied and you need to lock your bike to something thicker like a lamppost, you may not be able to do so with a U-lock.

This is where chain locks come into play.

Chain locks, thanks to their flexibility, can be used to secure your bike to a variety of anchors.

In many cases, chain locks are also easier to carry compared to U-locks. This flexibility, however, comes at a price. The best chain locks are the thickest, and the thickest chain locks can weigh well over 10 lbs (4½ kg).

What’s the Best Way to Lock Your Bike?

Before you even get to locking your bike, look around.

Will you lock the bike in an area with high foot traffic? Are surveillance cameras on nearby buildings pointed at the bike? Or, better yet, can you see police patrols, security personnel, or doormen nearby?

Make it harder for bike thieves to steal your bike by making it obvious to others when they target it.

Lock your bike to a bike rack, city fence, or lamppost. It must be anchored to the ground, high enough that the thief can not lift the bike over it, and thick enough that he or she can not easily cut it with bolt cutters.

Always wrap the lock around a tire, the frame, and the object. For maximum security, use two locks: one for the front wheel and the front part of the frame; the other for the back wheel and the frame’s triangle.

If you only have one lock and quick-release wheels, consider taking the front wheel off and locking it together with the rear wheel and frame. Otherwise, it’s just too easy for someone to steal it, especially if the rims or tires are expensive.

Be sure to remove all accessories of value that can be stolen from the bike despite the fact that it is locked. This includes lights, velo computers, and other whatnots.

Final Words

When choosing a lock for your bike, you should choose the smallest lock that will fit through the wheel, the frame, and the rack, fence, or lamppost you’re locking your bike to.

U-locks are the most secure, but the least flexible. Chain locks give you flexibility at the price of extra weight. Cable locks… leave them to those who need to lock their bike on the race track.

By Dim Nikov

City dweller. Recreational cyclist with a knack for writing. Always trying to find the right balance between life and bike.