This is a gorgeous ride over Passo San Osvaldo, to Erto above Lago di Vajont, then steeply up Val Zemola. It was not too bad of a surface even on a road bike, all the way to Casera Mela and a bit beyond. Previously I'd MTB'd it and went further north toward Rifugio Maniago. Wonderful scenery and good exercise in pristine air. Love it.