I just got a Kryptonite U-Lock to replace my "lost" chain. It's four
pounds and I don't want to keep carrying it around. I used to leave my
lock/chain around the fence where I locked the bike but the folks who
owned the building decided it shouldn't be there anymore and discarded
it one day (after telling me that it was ok to leave it there two
years earlier).

I moved to a new bike rack nearby, but I'm not sure about just leaving
the ULock there. While they are supposed to be pretty well theftproof,
perhaps someone would like to practice on it? And it's exposed to the
weather, which was not the case in my old location.

Still, l lugged the lock with me today and was very sluggish; four lbs
does seem to make a difference. I had it in the saddle bag; I'll have
to mount the bracket and see if the weight distribution makes a
difference. There is a LOT of weight on the back of the bike, most of
it being me.