I just found a goldmine of valuable biking route information.

Check this out:
Bike Rides Out of Pittsburgh: over 400 bicycle rides from .6 to 110 miles richly illustrated includes maps

THe linked PDF doesn’t have maps, but the route descriptions are good enough to keep one busy for a summer or two! I found it via this article in cycling news:
Tour de Pittsburgh: Pittsburgh’s Cool Cycling Culture, while doing a google search on this really awesome organization
FreeRide Pittsburgh: non-profit recycle-a-bike shop that enables people of all ages to obtain, recycle, and maintain bicycles.