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I know that similar questions have been asked here, but I can't find a question with the exact same problem encountered here.

My bike was left locked during a week or two of sub-zero temperature, and another week when my wheel was punctured (almost three weeks I think). And the day I started riding it again, I felt the lock started to jam but managed to lock the bike anyway.

Now since a week ago I cannot unlock it: The key goes in but doesn't turn at all (I bought the lock less than a year ago). I've suspected that water froze inside the lock, and so I've applied some water displacer in it (gt85) which has worked last time it has jammed, but not this time.

Lock

Is there any hope to unlock it if I use a lubrificant? And what type of lubrificant should be used?

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  • Possible duplicate of New D-lock failed locked up
    – RoboKaren
    Commented Apr 1, 2018 at 18:42
  • @RoboKaren But for me the key doesn't turn at all.
    – Hakim
    Commented Apr 1, 2018 at 18:57
  • Depending on the temperature the lock could still or once more be frozen. There's this special fluid for frozen car-locks that you drip into the keyhole, mainly isopropylic alcohol.
    – Carel
    Commented Apr 1, 2018 at 19:14
  • @Carel It's not as cold as it used to now (it even goes above 10C during the day, and it's still around 5C during the night). I saw that bike shops sell Lock De-Icers, maybe I should give it a go.
    – Hakim
    Commented Apr 1, 2018 at 20:24
  • You need to bring it inside where it can warm up for several hours.
    – Daniel R Hicks
    Commented Apr 1, 2018 at 23:40

2 Answers 2

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I've finally managed to unlock it thanks to the WD-40 penetrating oil, which the bike shop I bought the lock from advised me to use.

I suppose it was getting a bit rusty inside the lock mechanism, that's why the key couldn't turn.

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  • 1
    Great work. Now replace the lock before it fails even harder, and strands your bike somewhere.
    – Criggie ♦
    Commented Apr 3, 2018 at 0:31
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What's the temperature now? If it's been above freezing for a while, lots of GT85 into any opening is a good start, then jiggle the key. If it doesn't feel like it goes in all the way (and is symmetrical) then try rotating 180° before reinserting. Leaving the oil to penetrate also helps. For short-term lubrication, you just want something light and mobile; once you fix it, I suggest you oil it with whatever you use for your chain.

If it's still below freezing, there is such a thing as lock deicer. It's isopropyl alcohol. The problem can be getting it to the right place. This is an effective degreaser, so re-oiling the lock afterwards is a good idea1. It can be hard to deliver enough heat unless you can get power there: a hairdryer (or heat gun on low) can be good, but naked flames are generally a bad idea (especially if you've just doused it in oil/isopropanol). Heating the key or a similar piece of metal can help, but only if the keyhole is frozen, not if the mechanism is frozen further inside.

Where (my) old question may come in is that a good smack with something solid might help anyway try hitting one end , then jiggling the key, the other end, each side...

A couple of other things to watch out for:

  • The key might not be going in all the way (a bit of grit in just the wrong place). Again, squirting a suitable liquid right down the hole can flush it out
  • It may even go in too far. One of my locks sometimes doesn't turn (a Kryptonite, actually the replacement for the Abus that failed locked up). The fix for that is to pull the key out a hair's breadth.

A note for the pedantic: Yes, graphite powder is better for locks in the general case. But it doesn't keep moisture out, which is why many bike lock manufacturers recommend oil.

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  • The temperature now is 5-15C (UK's spring temperature). The lock jammed last Sunday, so I've applied GT85 in it on Monday, Tuesday, and then I was away for a few days. Today (a week after it has jammed, Sunday) I tried again to unlock it (without applying the water displacer), but the key still doesn't rotate. I feel that it's going in all the way, and yes the key is symetrical.
    – Hakim
    Commented Apr 1, 2018 at 20:03
  • I think I should visit the Halfords shop where I bought it from. They're the ones who suggested to use GT85 when I bought it, although to be honest I didn't use it since the last time it's jammed. The good thing is that the bike is stuck at Uni, so worst case scenario maybe the security could help me break it (Though, I hope I can save the lock).
    – Hakim
    Commented Apr 1, 2018 at 20:07
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    It sounds like you're in a part of the UK with a similar climate to me (as opposed to say the Scottish Highlands, where my friends were above the snow line today). At least that means you don;t have to worry about it being frozen any more
    – Chris H
    Commented Apr 1, 2018 at 20:08
  • I don't suppose you've got access to liquid nitrogen have you? Freeze until brittle and smash. The shop/manufacturer wanted the remains of mine back when it failed so I couldn't try it myself. If it's quite new (and it looks like it might be) you may have some luck getting it replaced
    – Chris H
    Commented Apr 1, 2018 at 20:10
  • No I don't have liquid nitrogen. If I manage to unlock it (or if I buy a new one), do you suggest that I apply both the water displacer and the same lube I apply to the chain (Muc Off Wet Lube) to it, to avoid having the same problem in the future?
    – Hakim
    Commented Apr 1, 2018 at 20:15

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