I grew up in Pittsburgh and lived there until 1994. It is, in my opion, by far the most hostile city for cyclists that I have ever seen. I used to bike commute between downtown and Lawrenceville/Shadyshide/Highland Park and on at least three occasions had objects thrown at me by motorists (some hits, some misses), was invovled in two physical altercations with motorists (nearly broke my arm tearing one guy's side view mirror off) and was deliberately run off the road by a pickup truck (never caught up to him). Each of these incidents occurred in broad daylight during commuting hours and in full view of other motorists. Heck, I don't blame this guy for commuting in his car. If I was still cycling in Pittsburgh I'd probably be dead.
Northern NJ/NYC and greater Boston, other places I've lived, are much bigger but also much more cycle-friendly (again, my opinion). I currently live in CT and bike commute year-round. Drivers here are especially courteous. Hopefully Pittsburgh has changed since I left in 1994 but if it hasn't then I think you need big cojones and a suit of armour to cycle commute there.
By the way, I still like the city and root heavily for the Steelers and Penguins. Go Pens!