This is a fun ride from Sertig at the end of the Sertigtal Valley to the little town of Clavadel above the Landwasser Valley.
The first half is an easier singletrack. Most of this singletrack is through forest so you won't have the views you get from some of the other trails in the Davos area, but this will allow you to concentrate on the ride, and you can pick up some speed on this trail (just be careful of hikers!).
Once you cross a suspension bridge over the Wittibach Creek at about 2.5 miles, you'll begin the 200 m (600 ft) descent into Clavadel. Shortly after the bridge, the singletrack gives way to doubletrack and the forest gives way to farmland so you'll be able to see the Sertig Creek down in the valley. The doubletrack continues for another 1.5 miles and then this becomes a paved road (Clavadelerstrasse) into Clavadel.
This makes part of the Rinerhorn Loop (Trail #647) together with the Sertig to Rinehorn
segment on the opposite side of the Sertigtal Valley. You could also take the Postbus (most have bike racks) to the restaurant at the end of the Sertigtal Valley where the ride begins.