Crack A Combination Bike Lock In Under 30 Seconds

If you ever forget the combination to your bike lock, here's how to open the lock — without any tools required. A word to the wise: You might also consider getting a more secure kind of lock for your bike.

The video shows how to open a standard four-digit bike combo lock by looking for the gaps between the numbers.

Obviously you should only use this hack for your own lock (and not for stealing bikes). It's a good idea to learn about lock picking of all kinds to increase your security knowledge.

If you're looking for a more dependable lock, check out REI's guide to choosing a bike lock and the BBC's bike security tips.

How to crack a combination bike lock in under 30 seconds [WonderHowTo via Reddit]


    There is no legal use for this so called hack and it only serves to encourage theft. Shame on you LH for promoting it.

      No legal use? How about for when you forget the combination to your own lock?

        If your going to forget the combo, buy a lock with a key.

          that makes perfect sense!


          Once you have mastered the art of knowing exactly what things you're going to forget an an indeterminate time in the future, please let me know.

          If you're the kind of person to forget a combo, you're just as likely to lose a tiny key.

        I forgot the code to mine after I locked it up for winter

      You do realise lockpicking is a valid hobby and that this is just an extension of that?

      Despite what any of these clowns say, +1

      You didn't ride your bike to school, did you?

      One of the many 'friendly' tricks to pull on classmates was to lock their bike to something, then watch as they tried to work out what to do. That's how I taught myself the above 'hack' - joke was on them if you rode off with their lock.

      Ding, ding, ding here comes the fun police

      How about drawing attention to the fact that standard combination bike locks are not secure/reliable?

      I disagree. When I was still at high school, I would cycle to school every now and then, I used to forget my combination quite often when I'd stop cycling for a while. What I did was, before I took my bike out the next morning I'd grab the lock and work out the combination by doing this. It worked for me and I've never stole someone else's bike by using this technique.

      Therefore, it does serve a purpose.

      just to feed your mind, if you know this exploit exists, then one can begin to contemplate why this exists, and remove the exploit in further lock models. To ignore that this can happen would do no good for improving further locking mechanisms.

      In short, you learn, analyze why it happens, and break it apart to improve on later versions

      I forgot my combo after the winter my bikes in my back aka im legaly using this for personal reasons e.e

    What friggin gap? Oh never mind, now I have to buy a more expensive lock, thanks LH

    Yeah I wouldn't get too attached to your laptop kensington (sp?) combination lock either. Certainly not the same "trick" but still just as useless.

    Sorry to burst your bubble there is a much easier and quicker method that my friends and I used over 20 years ago that works in the dark or even without looking as long as you know which end to start.

    Pull the two chains lightly putting tension on the lock and rotate the first number, when it suddenly feels free the roller is in the right spot, repeat for numbers 2-4. It will take you about 10 seconds to "crack" the lock that way.
    You can also remove the retaining clip and change the order of the numbers trying the 24 different combinations until you find the one that resists this technique the most. Then if your really obsesive you can sandpaper the pins changing the clearance so you can no longer work from 1-4 making it slightly harder.

    BTW neither of these techniques work on the 5 digit comination locks.

      Haha, i was about to write the exact same thing. I figured this out myself a few weeks ago when I forgot my bike lock combination. Just put some tension on it and started flipping the combination numbers around until it opened. took about 15 seconds!

      Yup - works like a charm this one - saved me only a few weeks ago when I got my stuff out of storage (turns out I was one digit out but couldn't remember and it was getting dark and still had heaps to move). The gap method does work but is much harder and doesn't work on all combo locks.

      BTW a key is MORE likely to get lost than forgetting a combo I have found, but they are more secure.

      Your hack is not quicker or easier it just relies on feeling the gap instead of seeing it

    I don't usually lock my bike and the other day I forgo my combo so I had to go back and cut the lock, I felt like such a criminal

    If you're using a cheap crappy lock like that one, a swift kick should open it.

    My son lives with his mom visits limited. I lost combo and he did as well. This helped me open his lock so he and a friend could go and not worry about someone stealing their bikes. I'm not interested in taking what is not mine
    Just preserving what is

    Pulling both sides of the lock method, i am trying for my cycle ( i wrote the lock number and saved as a contact in phone and recently had a phone reset to improve performance :)), out of the 4 rings, first and second rings are very loose whatever their number are and the 3rd and 4th are always tight again irrespective of their numbers. any help.


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