This is a scenic, hilly run along a quiet gravel road, with steep mountains on both sides. The Via Val Roseg runs out of Pontresina, a pretty mountain village located 6 km east of St. Moritz. The wide, gravel road runs for 6.6 km to Samedan, through a pretty valley with fantastic mountain views. It is a steady climb, rising 220m, with modest grades.
Loop Option: For a bit of variety, you can take the Chesin da Lein, which is a forested path running parallel to the Via Val Rose on the other side of the river, for the ~1.5 km out of Pontresina.