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Overcoming the Threat of the Bump Key: Protecting Your Self-Storage Facility From This Theft Device

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Padlocks vs. Disc Locks

Most self-storage operators these days realize that a padlock provides little more than a nuisance to an amateur thief, because its shackle can be cut with an ordinary bolt-cutter. Because a disc lock has a protected shackle, many operators and security experts believe it to be a significant security upgrade to the padlock.

That may have once been the case, but if the disc lock uses the same kind of key and keyway as a standard padlock, the bump key has changed the game. It easily opens any lock that uses a pin-tumbler keyway, the keyway found on most disc locks. With a bump key, disc locks are just “round padlocks” to a thief. You need to know this, and you need to have a response for your customers.

A bump key can open a pin-tumbler disc lock just as easily as it can open a pin-tumbler padlock.

Locks That Cannot Be Bumped

The bump key compromises the standard pin-tumbler keyway, found in the vast majority of “thief-resistant” disc locks on which the self-storage industry has come to rely. A disc lock can provide a powerful physical barrier, but with a vulnerable keyway, that barrier is little more than an illusion.

“Bumping is a vulnerability to many standard locks, and that’s why we educate experts on proper steps that can be taken to minimize the risk,” says Clyde Roberson, director of technical services at Medeco High Security Locks, an international lock manufacturer. “Not all locks can be bumped. Consumers need to know the difference.”

Fortunately, there are locks that cannot be bumped. These work through rotating detainer discs and a sidebar rather than pin tumblers. The detainer-disc keyway, developed nearly 100 years ago, is built around a series of seven to 11 discs. Each must line up with a sidebar to rotate the cylinder and open the lock. There are no pins or springs to bump. A detainer-disc keyway works in a padlock, a disc lock or a cylinder lock.

A lock such as the Medeco “biaxial,” which requires the pins to be lifted and rotated precisely, is described as “bump- and pick-resistant.” Medeco developed the biaxial in 1985 to defeat the bump key. With teeth and pins cut at angles, the pins must be rotated just so to open the lock. 

This year, Master Lock introduced its version of a bump-resistant keyway. It’s important to note that both the Medeco and Master Lock solutions are recent developments, and there are hackers who insist they have defeated the Medeco biaxial. Only the detainer-disc sidebar system has been successfully field-tested for nearly 100 years. According to Frank Minnella, CEO of Lock America International, the system was invented in Finland in 1914, and has never required modification to prevent bumping. 

Meet the Challenge

Google the term “bump key” and watch the videos. Then contact a lock manufacturer and ask about the bump key―in particular, what products it has designed to meet this challenge. It’s a good idea to do this before one of your tenants asks you the same questions, and certainly before an intruder or one of your customers decides to try out key-bumping at your facility. Of course, since there will be hardly any evidence that a lock has been bumped, you may not have to account for key-bumping until a customer reports a mysterious theft. 

Rich Morahan is a marketing consultant for Lock America International. He frequently writes and conducts seminars on self-storage marketing and security. To reach him, call 617.240.0372; e-mail; visit

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