This rocky-at-times forest road climbs through the heart of the Grand Forest in the Parco Naturale della Gran Bosco di Salbertrand (Nature Park of the Grand Forest of Salbertrand) to the Col Blegier (pass). Because it's a forest road, the trail is not rocky or difficult, but there are 640 m (2,100 ft) of climbing packed into this 7.7 km (4.8 mi). Coupled with the overall altitude, this is an aerobic challenge!
At around 2 km (1.2 mi), you'll reach a road intersection. Continue to the right towards Col Blegier. There is a particularly steep short climb just after this. At around 3.7 km (2.3 mi), the Strada dei Cannoni (5)
enters from the left. This is a former road, which is now singletrack, but it's better done as a downhill segment (i.e. ending at this point).
Your reward for reaching this point is a longer 0.8 km (0.5 mi) 120 m (400 ft) climb to an intersection known as the Ferro di Cavallo (horseshoe) because of its shape. Here there is an intersection with the Lago Luane (4) trail, also best done as a downhill, but in this case you're at the top of this trail.
Continuing from Ferro di Cavallo, you've still got a steady climb of 200 m (650 ft) to the pass at 2,381 m (7,811 ft). Just before you reach the pass at around 7.2 km (4.5 mi), you reach the treeline. Here there is a peat bog (Torbiera del Blegier), which forms an important habitat for animals and a rare carnivorous plant. Continuing on the main forest road to the right of the Torbiera, you'll shortly reach Col Blegier and the Assietta Road (Unpaved Section)
If you haven't already, take some time to admire the views across the val Susa. Consider integrating this road into the Gran Costa dal Sauze d'Oulx loop.