This ride is through beautiful country with a gentle upslope. And of course kids love trains, so they'll enjoy seeing the trains pass on tracks that roughly (but not too closely) parallel the trail.
This trail is the first segment of the Bernina Express
ride which is marked with the standard red and yellow waymarking signs as trail number 673. This is a gravel bike path that climbs the Bernina Valley at a gentle grade (about 5%), paralleling the tracks for the Bernina Express
train until the Morteratsch station.
The path passes through some pastures so you may encounter some cows and electrified gates that you must open and close. The cows are generally docile, but be more careful around mother cows with calves (and watch for cow droppings).