See the full relation Colico Piano - Alpe Mezzo - Alpe Grigiaia - Colico Piano (Lago di Como) - beautiful, middle difficult path with downhill (class 2 in german STS) - cyclable for XC bikers with some experience.
Beautiful MTB trip, see details on our YT movie (also many films from Alps, Apuan Alps, ferratas, Polish, German and Czech Mountains). First plan seciotn setiero Valtelina, than asphalt uphill, above 1000m mountain uphill (about 6-15%), the downhill with singletrack (up to 20% steep). Asphalt at the end.
take camera, full suspension bike, isotonic powder (water available from mountain rivers)