Well, got around to checking out what is what. To keep it simple, I started at the river and worked up to the park. Check map http://www.usatf.org/routes/view.asp?rID=226993
For the most part, the path is pretty much a goat trail within the old R.R. right of way up until the finish point. Large gravel, roots, hard packed dirt and grass. Mountain Bike path for sure, but I did it with 400c on my hybrid, so it not to bad. No Tour de France speeds
At the finish point you will find a fence with a partially chain closed gate, enough room to get the bike through. This path is wide hard packed dirt, small stones and runs to the road at the North end of Trout Pond at Seneca Park. Nice nature run, ran into a doe on the goat path.
If you skip the the goat path and take Seneca Park Ave at the chained gate to St. Joseph St. You'll find a long fairly steep grade that runs most of the length of Van Voorhis Ave to Thomas Ave. A killer for my wife at this point, so the goat path is great. heheheheh