We started from Campo Carlo Magno, at the Grostè cableway. Get off it at the highest station and turn left on the trail n°316, descending towards the Tuckett refuge. The trail is almost all over the stone, panoramas on the Presanella, Adamello and on the Brenta Mountains are astonishing.

We reach the refuge Tuckett after 4 km, the difference in height is affordable (descending 300 meters, ascending 100 meters). There is also a hostel, it could be possible to stay here for the night. We just stopped for lunch (here we had the best lunch of our holiday: "polenta" with cheese and mushrooms), before keeping descending towards the Vallesinella refuge.

The distance between the Tuckett and the Vallesinella refuge is 5 km, descending in height for almost 800 km. From here you can take the bus to come back to Campo Carlo Magno, closing the ring road to the starting point.
Check http://www.pnab.it/vivere-il-parco/come-muoversi/con-la-mobilita-del-parco/mobilita-vallesinella.html (italian language) for info about the timetable of the bus.