This trail begins in the mountain hamlet of Strassberg and ends at the Berghaus Schifer (mountain hut) well above the village of Serneus. There are restaurants at both ends of the trail offering a break from the long climb (and equally long descent) over the pass no matter which direction you have come.
There is nothing in the middle but sweet singletrack through the pass itself and probably more than a few cows.
From Strassberg, the first mile or so is on doubletrack until you reach the last farm. Once the trail becomes singletrack, there are a few short but very steep (especially at this altitude!) sections before you reach the pass. Right at the pass, you'll pass by the Grünesee (Green Lake) where you can make a bath in the summer.
From here, it is all downhill to the Berghaus Schifer except for one climb of about 15 m (50 ft). The descent is pretty steep, so hopefully you've checked your brakes before the ride. The trail is singletrack down to the first farm and then it transitions to doubletrack.
At about 4.25 miles into this segment, the route leaves the road and heads onto another singletrack about one mile long which passes through a forest. You can look for the sign for route 631 Durannapass, but this might be easy to miss if you are going too fast! The singletrack ends at the Berghütte Chesetta (mountain hut) and then it follows the Schwendiweg forest road down to the Berghaus Schifer.
From the Berghaus Schifer, you can take the road down towards Serneus and Klosters, or take the Klosters Overlook
Trail to wrap around the mountain towards Davos. There is a lift from Berghaus Schifer to the Weissfluhloch, but it doesn't seem to operate in the summer season.