The two you mention are in the South! But you are right in that the network of lines which connected the Caledonian Railway (Princes Street) to the docks at Leith and Granton are almost all cycle/footpaths.Most of Edinburgh's local lines have become cyclepaths particularly in the north of the city. The best known probably being the Innocent Railway and the Balerno line along the Water of Leith
And also the line towards Penicuik.