Sometimes I hear people use disk lock and the horseshoe mini u-lock interchangable. I have a new york chain and it came with the mini house shoe u-lock, so I am going to assume you have the same[unless it came with the krypto disk[round]lock. So just in case http://www.nybma.com/faq/question3.htm This link is a good link and may raise another problem with your lock that you might not suspect.