Except for between Fostburg and Cumberland the elevation change is almost imperceptible. I would recommend riding from Pittsburgh to Cumberland, then you would have the "glide" all the way from the divide into Cumberland. If you decide to go the other way there is a tourist train that takes you from Cumberland to Frostburg. That gets you most of the way up the hill.

Let me know if you need any tips or help at the Pittsburgh end. You should plan for a least a full day here. Lots to see.