Yesterday evening, my Kryptonite U-Lock was pretty stiff when I unlocked it after work. The key turned fine, but removing the shackle from the crossbar took a few minutes of pulling and jiggling. I eventually was able to separate the two, ride home, and lock the bike up outside. This morning, I couldn't separate the two, even after 10 minutes of finagling. The key turns 180 degrees and presumably the lock is open, but the two parts will not separate. I put some tri flow on the joint, no luck. What is causing this? How can I remove the lock, and prevent this from happening again? For what it's worth, these have probably been the two coldest days of winter so far in my area.
1I doubt triflow would have much effect on ice.– Criggie ♦Dec 14, 2017 at 0:57
2Use an alcohol-based lock deicer. Sold in small spray bottles in auto parts stores and the like.– Daniel R HicksDec 14, 2017 at 1:02
Sounds like you have moisture in there somewhere and its frozen. Try pouring warm (not boiling) water on it from a jug.
When you get it open, take it inside, dry it, and store in a hot water cylinder cupboard to drive out moisture. If you don't have a HWC then 30 minutes in a normal oven on super-low temperature would do. Or even putting the open lock in a sunlit window for a whole day.
Once its dry you need to keep the moisture out - I'd use a lot of grease like White Lithium.
You also want to check the seals and perhaps arrange the lock with the keyhole facing down, and the curved part of the D would be lower. That way rain water won't run into the lock along the sides of the D.
Keyhole and D loop down is not how the lock is arranged. That would be a silly design as locking would block access to key hole. Dec 14, 2017 at 9:11
@Paparazzi you're right on the Kryptonite and Masterlock locks I have, which have the keyhole oppostie the holes for the cruved part. For a D-lock with the keyhole in the end of the crossbar this advice about keeping ti dry could work.– Chris HDec 14, 2017 at 9:16
1Over or in front of a heater might be good too, depending on your heating. The lowest setting on an oven or even the air from some heaters may be too warm for a plastic coating (they're often vinyl which softens at quite low temperatures). Grease on the places where the two halves come together might also be a good idea once it's dry– Chris HDec 14, 2017 at 9:19
Pouring warm water over the joints worked to free the crossbar. The lock is drying out in a sunny window at my workplace right now. I will report back on whether White Lithium prevents this from happening in the future. The keyhole is on the crossbar, facing away from the curve of the D. So putting the curve down exposes the keyhole. But there is a keyhole cover, so maybe this will work. Will report back. Dec 14, 2017 at 15:13
2@MrBobinski you might benefit from cutting a short section of innertube, of a close-fitting size, and pulling it over the lock as a cover.– Criggie ♦Dec 14, 2017 at 19:22