That will keep you safe. Or a u-lock that is big enough to fit around the waist but not the tips. So that it isn't rideable.
A U-lock? Seriously? I don't mean to be cynical Nivek, but isn't that a bit overkill? I'm actually honestly interested if any one on here uses one of these. I have one for my bike and it weighs close to 10 lbs.
I've always used a simple retractable lock (fits right in my pocket). They're light and easy to pop on and off. Yes, the cable is a little flimsy but its kept away most of the Boston/NY doucheheads that migrate to the mountains I ride...
Just my $0.02.