From Chiusaforta over the bridge to Raccolana to your left. At the very end of the village a very small path leaves into the bushes and trees and follows the Rio Patoco up to Patoco (CAI 621). A lot of pushing the bike on this single trail. Before you actually enter Patoco the path takes of via the meadows uphill (still 621). From now on it is very difficult and steep and very little biking and lot of pushing. Along the way there are a few fountains, so you will have enough water.
You stay on CAI 621 all the way with a little more biking at the end until you reach Plan di Montasio, where you can have a nice rest. From there the paved road leads down to Sella Nevea.