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I've been biking for 2 months now with my U-lock still on my bike, it sort of gets in the way of pedaling sometimes and I'm kinda tired of it.

Does anyone know of any ways to get the remnants of the key out from the lock? Or is my only option to send this to the bike shop and have them saw it off?

I can provide pictures if necessary. I've been using a secondary chain in the meantime.

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    Pictures might be helpful, or just the actual brand and model of lock. Knowing what kind of key it takes and how broken off it is would help...
    – freiheit
    Sep 12, 2010 at 18:27
  • Also: do you have another key?
    – freiheit
    Sep 12, 2010 at 18:29
  • doityourself.com/stry/remove-broken-key
    – freiheit
    Sep 12, 2010 at 18:38

7 Answers 7

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It seems like you have 2 basic choices: (1) remove the key from the lock and unlock it with a backup copy of the key, (2) defeat the lock. Option #2 is an awful lot like asking how to steal a bike... Also, option #2 really depends a lot on the specifics of your lock.

  • Lubricate the lock
  • If there's anything sticking out, try grasping it with needlenose pliers, nail clippers or something like that
  • If there's nothing sticking out, you can try a thin bit of metal along the side of the key with the teeth. Or a couple sewing needles, or maybe a pair of thin tweezers.
  • Also worth trying giving the lubricant a little bit of time, then bang the lock against something, trying to get the key to fall out.
  • May be worth heating the lock; it may expand enough to release the key
  • A locksmith might be able to get the broken key out. No idea if that would be more or less than the bike shop cutting it off.

If none of those things work to get the key out, you have to really defeat the lock. There are leverage attacks, but those are likely to break the bike.

  • An angle grinder will get through it in seconds. If it's a really good lock you might have to make two cuts. Got any friends into power tools? Someplace else you can rent or borrow power tools from? You'd need to use a vice to secure the lock so it doesn't move, and be careful not to hit the bike. And all the other appropriate safety measures...
  • An electric hacksaw would, I think, take a bit longer but still not tire your arm out.
  • A hacksaw should work, but it's slow. It's likely that the price of a new hacksaw with the right kind of blade could be as much as taking it to a bike shop... Might need a second blade...
  • If it was possible to close the lock without the key inserted, it should be possible to defeat it with a shim: cut away any rubber from the locking end of the U, cut a wide strip of aluminum from an aluminum soda can, wrap the strip around the U, slide it into the lock
  • If you can get a car jack inside the lock without hurting the bike, you can spread the lock open. Most U-locks only lock on one side, the other side is an L joint, so if you spread it far enough the L will release. Or it might just break the U. Be very careful with your bike doing this, of course.

Disclaimer: I've never done any of these. I'm mostly only aware of those techniques in order to know what to look for when buying a bike lock. Only lock I've ever defeated was a simple combination lock back in the 80s that you could pull on and slowly spin the dials to feel what the combination was.

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What every you do, make sure you got good ID with you and be nice to the police if they give you a visit while you are trying to remove the lock.

If you have other keys, be very carefully not to damage the lock, otherwise a lock smith will find it harder to get out the broken key, otherwise,

Sorry, any good lock should not be easy to defeat, if the cost of defeating the lock is less than the 2nd hand value of the bike, then you should have brought a better lock in the first place!

Unlike someone stealing your bike, you:

  • Don’t mind spending a long time defeating the lock,
  • Don’t mind making a lot of noise
  • Don’t mind “going equipped”

So you do have a chance…

You may find if you phone the direct phone number of your local fire station and ask for advice they will be helpful. However do not call the emergency number.

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    No lock is impossible to defeat. Ideally a lock should slow down a potential thief, make their attempt obvious to passersby, and require special tools. None of those are real issues in your own garage/backyard... I like the fire station suggestion. Probably worth mentioning police, since either one could be responsible for things like removing illegally locked up bicycles and might be willing to help.
    – freiheit
    Sep 13, 2010 at 20:16
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    The question clearly states that the bike is not attached to anything, making most points in this answer moot. Being able to bring a bike to a location to open the lock is a HUGE advantage over a thief
    – Andrey
    Jul 15, 2014 at 14:35
  • @freiheit In the UK, at least, an "illegally" parked bike wouldn't be a criminal matter so the police wouldn't get involved. On private land, the landowner would be responsible for removing abandoned bikes; on the streets, it would be the city council's responsibility.
    – David Richerby
    Feb 15, 2018 at 19:53
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    "if the cost of defeating the lock is less than the 2nd hand value of the bike, then you should have brought a better lock in the first place!" - there is no practical lock in existence that fulfills this claim for any bike better than BSO quality.
    – whatsisname
    Feb 17, 2018 at 4:11
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I once had someone steal my bike which was locked to a bicycle rack using a U lock. The thieves left the remnants of the lock behind (flaunting their lock defeating abilities at me, I presumed... as if stealing the bike wasn't by itself enough of a kick in the gut... those sons of a motherless goat!).

Examining the defeated lock, it appeared to have been cut through using a pipe cutter. So, if you decide you need to defeat the lock, that's one thing you can try. I've never tried it, I can't guarantee it will work (plus the lock I owned might have just been particularly vulnerable to that type of attack, I don't know).

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    Nah, they just had no reason to carry your broken lock around with them.
    – David Richerby
    Feb 15, 2018 at 19:54
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I had the same problem my key jammed in my lock while it was locked to a rail and I literally looked this up just so I could figure out how to get my bike free.

The answers here are over exaggerated and unhelpful.

I just asked my neighbor if he had a hacksaw or anything to get my bike lock off he gave me some bolt cutters. I just went there and two strong guys helped me. We placed the cutters right on the base of the lock and BAM my bike is now free.

Skip the hassle borrow someones bolt cutters and there you go.

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If the U-Lock has a circular key and you manage to get the remains of the key out then check out these YouTube videos of how to open one with a cheap biro:

If it's another brand with a flat key (or you can't get the key out), and you have access to an angle grinder then this might be of interest:

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This happened to my Kryptonite Series 2 recently. The key inserted fine and got stuck during the turn. I was able to unlock it by pumping the key cylinder with a lot of wd-40 and then jiggling the key vigorously for about 10 minutes before it would turn or remove.

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If the remnants of the key are still in the lock, your best bet is to get them in the right position (far enough but not too far in) and turn the piece to open the lock. The stub of the key may come in handy if you still have it, else try a screwdriver or similar. I've opened a few locks that way. Once you've opened the lock, banging it on the sidewalk might shake out the broken-off piece.

If you pushed the broken off piece in too far, try a dab of Super Glue on the stub (or other tool), being careful not to let it get on the inside of the lock, let it harden and pull out the piece of key far enough to turn the lock.

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