How thieves break bike locks – and how you stop them

At the station, someone walks along the row of bikes and barely looks at a single bike. He looks at the locks. What goes on in his head is a cold calculation, and you can influence it.

The need for this topic is large: in 2025, around 214,000 bicycle thefts were reported in Germany, and only about one in nine cases was solved (source: German police crime statistics (PKS) 2025). Behind almost every one of these cases is a lock that gave way. Our guide to bicycle theft statistics for Germany shows how the cases are spread across the cities.

So that we are talking about the same thing: break-in resistance is the ability of a lock to withstand an attack with tools, to raise the effort for the thief noticeably and thereby make him give up before the bike is free. This does not mean being uncrackable, it means time gained: a lock should not make the theft impossible, but uneconomical. Material, design and locking cylinder determine how much time you buy, and the parking spot determines how expensive that time becomes for the thief. So the rule is: no lock is uncrackable. Every good one is expensive enough.

How do thieves crack bike locks?

In everyday practice, thieves use four broad routes of attack: cutting, grinding, levering and manipulating the cylinder. We deliberately only name them here, without describing techniques, tools or procedures. What matters is the logic behind them, because that is where the countermeasures come from.

The following table is the map for the whole article. Read it column by column: every type of attack has a weak point it exploits, and a design it regularly fails against. That is exactly where your countermeasure comes in.

Why is time the real security?

A thief gives up as soon as the risk exceeds the expected gain. He does not want a challenge, he wants loot with as little effort as possible. Every extra hurdle shifts his calculation until the bike next to yours is the better option.

That explains why two factors only work together. A lock provides resistance. A good parking spot provides attention. A top-tier lock in a dark side alley loses against a decent lock in a busy square, because there every minute of work happens in front of an audience.

That is exactly why it helps little to search for the one uncrackable lock. There is none.

What there is, is a chain of decisions that drives up the effort step by step: the type of lock, the way you lock up, the location, the visibility of a marking. Our guide “Parking your bike safely” sorts out which places are how risky in practice.

Which locks best withstand an attack?

The most resistance comes from D-locks made of hardened steel, followed closely by high-quality folding and chain locks. As a budget, the rule of thumb has become to put around 10 % of the bike’s value into the lock. Our guide “Types of bike lock compared” compares the designs in detail; here only their behaviour under attack counts.

As you read, watch the third column. It is the more honest one, because every design has a gap that product pages rarely talk about.

And what about test seals and security ratings? They help with the pre-selection, because they make break-in resistance comparable. But do not rely on them alone, because manufacturers use their own scales, which do not match one another. Compare within a brand, not between brands.

How do you lock up so that tools cannot get a purchase in the first place?

The best lock loses its advantage if it is fitted wrongly. You see three mistakes at every bike stand: the lock sags loose, it rests on the ground, or it secures only a wheel instead of the frame.

All three give the thief exactly what he needs: a surface to work against and room to work. A lock that sits tight against the frame and high above the ground takes both away. He then has no counter-bearing, no room to lever and no comfortable working height.

So always lock the frame to a fixed object, pull the lock as tight as possible and keep it off the ground. Our guide “Locking your bike properly” shows you the most common mistakes step by step.

Sounds trivial. But it changes more than moving up to the next most expensive lock.

Does a second lock really help?

Yes, if it is a different type. Many thieves work with one tool that they have mastered and that is easy to carry unnoticed. Two different types of lock force them to bring two tools and to work twice.

Two identical locks, on the other hand, achieve very little. What stops one also stops the other, and what breaks one breaks the other straight away. The time gained is then more of a small addition than a real leap.

In practice that means: D-lock plus chain, or folding lock plus D-lock. Ideally, the second lock also secures the front wheel, which otherwise disappears first.

The catch: two locks weigh something. If you leave them at home because of that, you have gained nothing. Better one good lock that always comes along than two that stay in the hallway.

What is behind the freeze-spray myth?

The internet classic goes like this: you can freeze a bike lock and then smash it. In practice this is barely relevant, because the steel in common D-locks has enough quality to withstand blows, and because the attempt is loud and awkward. Thieves take the easier route, and that leads through weak locks, not through chemistry.

A second myth is just as persistent: expensive equals secure. Price correlates roughly with resistance to attack, but the decisive factors remain the design, the steel quality and the way you apply the lock. An expensive lock dangling loosely around the seatpost area protects worse than a mid-range one that sits tight against the frame.

And what about combination locks? They are convenient, but resistance is not decided at the number dial, it is decided at the shackle or at the links. A combination lock with a thin cable remains a thin cable.

In short: the myths distract from what matters. What matters is steel, fit and location.

Is breaking a bike lock a criminal offence?

Anyone who breaks someone else's bike lock in order to take the bike is generally committing an especially serious case of theft under § 243 StGB (the German Criminal Code). Breaking a security device is precisely the feature that lifts the act above simple theft. Bike theft is therefore not a trivial offence, even if it is often treated as one in everyday life.

This has two practical consequences for you. First, filing a police report is always worthwhile, even if the clear-up rate is low, because only a reported bike can be matched to an owner during a check at all. Second, for that you need proof that the bike belongs to you. What to do in which order if the worst happens is set out in “Bike stolen, what now?”.

Incidentally, this does not apply to your own lock. If your key is lost, a specialist firm will open the lock, and you should have your proof of ownership with you.

Where does even the best lock stop helping?

Time for the uncomfortable truth: there are situations in which your lock can no longer do anything.

The quiet spot. Anyone who can work undisturbed and for a long time will technically get through any lock. That is exactly why the parking spot is not a side issue, but the second half of your protection.

Being carried off. If the bike is only connected to itself, for example via a frame lock, it gets carried or loaded up and opened somewhere else at leisure. Without a solid anchor point, no lock protects.

The anchor point. A top-end lock on a loose fence panel or a short post that the bike can be lifted over is a top-end lock with no effect. Check the point, not just the lock.

Afterwards. Once the bike is gone, no lock will help you. From then on, the only thing that counts is whether you can prove it is yours. Without proof, even a recovered bike often stays with the police, and reimbursement also becomes difficult. The pitfalls involved are shown in “Insurance won't pay for bike theft”.

How do lock, security marking and registration work together?

The most effective protection is a chain, not a single part. The lock costs the thief time, the parking spot costs him calm, a visible marking costs him the resale. A security-marked bike is harder to get rid of, because every buyer and every check can see the identifier. That is why many thieves leave such bikes alone.

The final link is provability. With BikePass you store your frame number, photos and purchase receipts free of charge as digital proof of ownership, shareable with the police and your insurer, set up in a few minutes and usable across the EU. If you wish, a tamper-proof security marking set with a sticker and QR code comes with it, which you attach yourself at home, with no appointment and no tools. How to combine lock, location and marking into one overall concept is shown on our page about theft prevention for your bike. If you also want to rely on noise, you will find the options in the guide to alarm systems and immobilisers.

And the man walking past the locks at the station? He keeps calculating, afresh at every bike. Your job is not to stop him, but to make sure his sums do not add up at your bike: a good lock, applied tight and high, a bright spot, a visible marking, stored proof. He will then simply walk on.

BikePass Editorial Team

We write about bike theft, security marking and digital theft protection – practical, without scaremongering and with real steps you can take.

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