I'm traveling for spring break and hope to bike around Houston and other places with a borrowed bike. I'm considering bringing a U-lock with me, but wanted to ask here if anyone had had any experience getting that through security in carry-on baggage. I'd rather not check the bag, and even if I did, the lock would be heavy and maybe make the bag over weight.
Anybody have any suggestions? I will be flying out of PHL (Philadelphia) and IAH (Houston) on Continental.
i tried to figure this out once, and ended up going for it. I did get through with no problem, but i imagine that isn't always consistent. there is no where that says that you can't. it most likely depends on who you get and if they think it could be used as a weapon. did you try calling the airport?
I'm a frequent flier & while I've never flown with a U lock, I have a hard time imagining them banning this. If you want to play it safe, just buy a U lock there and give it as a thank U to whomever is lending you the bike. U locks are cheaper than checked bag fees these days 
I would not expect to get it through, after all the hulabaloo over knitting needles, lip gloss, intrusive searches, and other nonsense, though I've never tried.
One of the arguments against letting grandma keep her knitting needles is that while she may not use them as weapons, someone else could.
Still, it's cheap, so if they do sieze it, you're out one, and can buy one there. I'd be interested to see what you end up doing and the results.
Regardless, have a blast on break 
Just bring it with, and if they say you can't take it, lock it to something there. Good chance you may be able to get it that way when you get back…Or at least make the whole thing humorous.
I've gotten through on several occasions with a U-lock. They'll likely pull you aside and do the "extra" searching though - it's a lot of metal to run through those machines.
I've traveled fine with a U-Lock. YMMV.
I've flown with a U-lock in carry-on baggage in order to get my checked bag under the weight limit. They did ask me what it was, and it resulted in a more thorough search of my bag but it wasn't a problem. They absolutely would not, however, allow a small set of allen wrenches.
I recently flew and rented a bike, which came with a u-lock. While I was there I bought a folding allen wrench set thinking that it wouldn't make it back with me. Surprisingly, I had no problems getting that (or a 12.5 ounce bottle of hand lotion) through security.
Wrenches of up to but not over 7 inches are supposed to be OK for carry-on, according to the TSA website. No mention of U-locks, but a heavy U-lock seems as much of a threat as brass knuckles or hand weights, and those are prohibited.
I had to throw away my U-lock at Chicago Midway, despite checking that there was nothing explicitly prohibiting them. Obviously mailing a U-lock back to yourself will be cost-prohibitive.
Carrying a tube of chammy cream in your bike box international is cause for alarm. No problems after you explain what it's used for.
