I have a Kryptonite U-lock and my key doesn't seem to be working, I'm not sure if the key is broken or the U-lock. How do I unlock my bike? Kryptonite isn't open and both the key and lock worked an hour before. (I have a theory that moisture inside the lock froze.)

  • 2
    Have a theory of hit it with a hair drier
    – paparazzo
    Feb 24, 2015 at 0:19
  • Tried WD40? Both on the key and the lock.
    – Elmer
    Feb 24, 2015 at 1:00
  • 1
    I'd try the hair dryer as well. Lock deicer may help too. Using graphite in the lock after you get it free is a good idea after warming it up and drying it out.
    – Batman
    Feb 24, 2015 at 2:45

3 Answers 3


This happened to me with a Kryptonite Evolution lock. I locked it, went for lunch, but afterwards the key just wouldn't unlock. After hours of oil, poking bits of wire, screwdriver waggles, help from strangers, I gave up. I tried again the next day, and gave up again.

In the end, I had to cut the lock with an angle grinder. Took 20 seconds tops. I took it back to the bike shop and they replaced it immediately. They said they replace about one a year on warranty.

They also recommended putting a bit of oil in the lock each month to keep it working smoothly.


I used deicer and WD-40. I think the WD-40 is what freed it enough for me to force it open. Then I wiped off a rust colored gooey film that it seemed to be getting stuck on.

  • Glad it didn't need an angle grinder!
    – Hugo
    Feb 25, 2015 at 13:55

Things I have tried with success on dodgy locks.

I found the angle of the lock makes more of a difference. Heaviest part towards the floor seemed more successful, though another lock like to be horizontal. There are some balls/bolts that pull in on lock. The angle can help assist

Pushing key in a varying depths and wiggling to free the lock.

Load of wd-40.

Pushing and pulling the Lock part while trying the key. Ensure the bolts are binding better.

Cool it (i.e waited till night)

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