I have a kryptonite key opening u-lock, opening the lock had recently bocome stiff. But now the bike is locked outside and I can't turn the key the whole 180 degrees, only 90 degrees. It won't open. I've tried lubricating it and re aligning the discs.

What's the easiest/ cheapest way of forcing it open?

  • Here are a couple questions that may help :) bicycles.stackexchange.com/questions/8262/… and bicycles.stackexchange.com/questions/884/…
    – FreakyDan
    Mar 26, 2015 at 17:45
  • you could try a car jack
    – PeteH
    Mar 26, 2015 at 17:52
  • 2
    Before you cut it tap it with a hammer on both ends. And tap it in on the U.
    – paparazzo
    Mar 26, 2015 at 18:09
  • @Blam any comment/answer that involves the use of a hammer gets a +1 in my book
    – PeteH
    Mar 26, 2015 at 18:16
  • 1
    An angle grinder is the best choice for speed and lowest chance of collateral damage. If you can't find one to borrow you can rent one. Or buy a cheap corded one at Harbor Freight for $15. (But if you can borrow or rent a cordless model it's much more convenient than the corded unit you'd get from HF.) Mar 27, 2015 at 0:29

5 Answers 5


Angle grinder. You should be able to cut through it in less than a minute. Make sure to wear eye protection.

enter image description here
(source: machinemart.co.uk)

  • 2
    and also be prepared for strange glances from passers-by
    – PeteH
    Mar 26, 2015 at 18:09
  • You'll get those no matter what you do. At least this method is quick (noisy, though). Mar 26, 2015 at 18:22
  • Be aware that when linking to external images, links usually break over time
    – Ferrybig
    Aug 22, 2018 at 14:06

Depending on where you are, consider having proof of ownership before you go dismantling a u-lock.

Before destroying the u-lock, see if tapping it with a pipe or hammer in various spots while jiggling the key does the trick.

If it's good and seized up, time to cut through it with an angle grinder. If you don't already have an angle grinder, Ryobi has some very inexpensive models.


Try a shot of graphite or "lock lubricant" in the lock mechanism and jiggle the key for a bit before destroying the lock. It may just be a bit rusty inside.


This is very location dependant, but police may remove it for you whithout charge, specially if it is locked to public urban furniture. (I know a friend of mine got his bike back this way after losing his keys) Of course you would need that proof of ownership.


Depends on which U-lock it is. Something like the Kryptonite Keeper might be hacksaw-able efficiently, but you're going to have to do a lot more work with a hacksaw to take out something like the Fahgettiboutit. Note that you'll need a blade which can cut steel.

Bolt cutters may also work on some U-locks. And angle grinders.

Theres also using a locksmith.

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