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How to Break a U Lock Successfully in 3 Different Ways

Fact checked by Teddy B.Miller

how to break a u lock

As you can tell, most U locks are built to have an unbreakable structure for high security of your possessions, such as door handles or bikes. That is why many people wonder how to break a U lock in a time-saving and cost-effective way.

Apart from the simplest and most popular approach of jimmying the lock with a ballpoint pen, there are other methods that involve applying force to your lock and breaking it down completely. Dive into this article to find out.

What You Need To Follow This Tutorial

Prepare either of the following tool sets:

  • A bolt cutter
  • An air spray and hammer
  • An angle grinder, gloves, and goggles

Step By Step Instructions


In our opinion, you should consider your preference and personal situation to decide how to break a bike lock. Here are the details for three methods:

Cutting U-lock using a bolt cutter

This method is probably the most straightforward of all. Find a bolt cutter and use it to grip one side of the U-lock. Then, apply pressure on the cutter’s handle until the lock breaks.

Check out this guide for more information on cutting a bike lock using bolt cutter.

Cutting your lock using an angle grinder

Step 1: Take necessary safety precautions

Because angle grinders create a lot of sparks and debris, you should protect yourself with gloves and a pair of goggles.

Moreover, make sure your working area has no flammable objects. You don’t want to start an accidental fire while cutting the lock.

Avoid wearing anything that can entangle with the grinder’s disc, such as jewelry. If you have long hair, tie it up as well.

Finally, check the disc of the grinder to make sure it’s in good condition.

Step 2: Start the machine operation

Next, familiarize yourself with holding the grinder; make sure you can maintain a strong grip on it. Use both hands to carry the grinder at an ideal angle of 15 to 30 degrees.

If you feel any slipperiness or exhaustion while cutting, turn off the equipment and stop using it for a while. Alternatively, you can ask someone else to operate the grinder.

To cut a bike U lock, turn the grinder on and position the blade against the lock. Once you’re done with the first cut, make a second one close to it.

This process requires some patience, but once both cuts are complete, the lock should be removable. Remember to turn off the grinder immediately.

Breaking your lock using a hammer and air spray

Step 1: Spray air into the lock’s keyhole

Before breaking U lock, you need to weaken it. With the air spray can in hand, spray air at the lock’s keyhole. Eventually, the lock will turn white and become cool to the touch.

Step 2: Break the lock using a hammer

Place the lock on a level surface and hammer the keyhole. It may take a minute for the lock to break, either on one side or both sides. Just keep on hammering, and the lock will fall part eventually.

Check this detailed guide here!

How to Open U-lock Using a Pen

If you don’t want to break the lock, you can open it with a ballpoint pen. Find a pen with a removable cap and a tube with the same diameter as your keyhole. Usually, a Bic pen should work.

Then, remove the pen cap and insert the tube end into the lock’s hole. Finally, twist the pen until the lock opens.

Note: Many modern locks (such as disc-detainer ones) are resistant to being picked, so don’t feel bad if this method fails. Consult a professional if you want to save time and avoid frustration from fiddling with your lock.



Why does air spray weaken U-locks?

Cold locks lose flexibility, and this change makes them less durable. Since air spray can lower the temperature of U-locks, it makes them more vulnerable to strong external forces.

How do I break a U-lock with a combination?

You can still use an angle grinder to cut the lock. Just follow the steps above.

How to secure my bike with a lock?

If you’re selecting a U-lock, the thicker it is, the better. Also, keep the U-lock away from the ground to prevent thieves from using bottle jacks. Avoid buying cable locks, and use security bolts for the wheels and saddle if possible.

As for chain locks, pick models that resist hacksaws and pair them with sturdy padlocks.

Another tip is to look for products with high security ratings. Some manufacturers send locks to organizations like ART and Sold Secure for testing, so you can look for their certifications.

Finally, even with the above measures, it’s important to park your ride in a well-lit area with security cameras and guards. Secure your bike to an immovable object and put it close to other bikes. Use two locks if possible, because the thief may see your property as a troublesome target and move on.

Can all bike locks be broken?

Unfortunately, yes. No product is infallible. An angle grinder can break through all locks if used long enough.


Are you clear on how to break a U lock after reading the provided information in this article? You get to decide the final method you will follow, but keep in mind that breaking or cutting the U lock will make this item unusable later on.

Do not be afraid to express what you think about this article in the comment section. And please spread the word to your friends and family if possible, so they can break their U locks easily as well!

Thank you for reading.

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