Originally Posted by
Myosmith
Think Schwinn Varsity. Ugliest color you can find with chrome fenders and mousetrap rack. Put a couple of Justin Beiber stickers on it and one strange colored tire on the front. You probably won't even have to lock it.
Really though, old 10-speeds and steel rigid framed MTBs make good college commuters and you won't lie awake at night wondering if you should have added just one more lock.
^this
Even cheap bikes, when new, will attract theives. Old, scratched up, well used bikes are much less likely to be stolen. Like metioned above, an older mountain bike with no suspension, or an old 10-speed are great choices.
But the most important thing to look for is fit... you have to be comfortable riding the bike. Make sure whatever bike you buy is comfortable to ride, and that you get proper leg extension (leg almost straight at the bottom of the pedal stroke with the saddle adjusted so there is at least approximately a fistful of seatpost out of the frame. Maximum of three or four fistfulls of seatpost out of the frame, depending on the bike.
Then - lock it up well (if you have a quick release front wheel then remove the front wheel, place it next to the rear wheel, and lock up both wheels and the frame in one go. THat way, if someone wants to steal your bike they have to cut the lock then reassemble it before they can ride away. There is no way to make a bike completely theft-proof, but you can make it so other bikes nearby are more attractive targets.