At my university, bike theft was a problem, but if you were smart, it wasn't too bad. I think (not positive) there was a place in the dorms where you could keep your bike. It was a locked storage room, but multiple people on the floor had access, it was not just your room. So, there was a risk involved. We had to register our bikes on campus, and like someone else said, just make sure you have no quick releases and lock the frame and wheel up. If you are concerned about the seat, just take it with you to class.

It didn't seem like the people who stole bikes really know what was a good bike. They just went for the easy target!