Re: How do you prevent your bike from getting stolen or messed with?
well, the first thing to do to keep your bike from getting stolen is to lock the garage. if you're gonna be lazy and leave it open, you might as well just leave it on the sidewalk with a "FREE BIKE" sign.
get yourself a good combination U-lock, like a Kryptonite. don't buy a cheap chinese one, get the real thing. cables and padlocks can be cut easy enough, but about the only way to open a u-lock is with a car jack (unless it's an old one cylindrical keyed one that you could open with a bic pen, but those have all been recalled.)
lock your bike to something secure. not a post that can be pulled out of the ground or unbolted.
if you can't lock it somewhere that you can keep an eye on it, make sure someone else can, in a high traffic area. it's less likely to get snagged if there's people walking by all the time.
unless you can find a locking gas cap, there's not much you can do about someone messing with it. vandals suck, and no matter what you do, if someone wants to mess it up, they could.
if you can legally register your bike and get a plate, do it. that way if it does get ripped, you can report it and it's in a database.
bottom line, if someone wants it, they'll get it.