My mother just commented on this. "You spent so much money to get a light bike and then you want to go and add a really heavy lock to it." I couldn't disagree with her. It is an unfortunate aspect of owning a bike. I was thinking of the Kryptonite Mini lock. It's supposed to be the bike lock for bike messengers. 3 1/2" x 5" and 1.6 lbs but as strong as a regular U-lock Problem is, I can't find one here. In fact, the LBS's here haven't heard of the them. I will probably be ordering one on line or picking one up while I'm in LA in May.