First post. Just got a new bike and a new lock, Kryptonite Keeper Standard 12mm U-Lock. Tested the U-lock several times in the house and seemed to work fine. First use in public, worked fine. Second time in public, today, went to lock the bike, inserted the key and it refused to turn and engage the lock. Then it refused to come out of the crossbar. So I gave up and waited till I was back at the house and after repeatedly jiggling the key, was able to remove it. Returning the lock but now I'm thinking for low security situations, just using a chain lock. If that u-lock had failed in the locked position, man what a headache. With a chain lock, I could just grab some bolt cutters and get the bike back. This would obviously only be for very low security situations, which in my case, will be most situations. Thoughts?