Originally Posted by
Torchy McFlux
Kryptonite U-locks are all made of hardened steel. Fastest and easiest way is with a portable angle grinder with a cutoff wheel.
You said it's an older one? Does it have a round key? If so, there might be a quieter way:
http://www.youtube.com/watch?v=t8XxcOj3Seo
I used to have an old U lock from Walmart that I lost the key to and tried the pen trick, it was a lot more difficult than that!