Davos is a mountain biking paradise. You'll find an extensive, well-marked trail system (look for the ubiquitous red and yellow signs) through the beautiful high alpine territory and then back down into the valley. Despite this, the trails never felt crowded, especially as you move away from the main valley.
All this is accessible with an excessively organized (otherwise it wouldn't be Swiss!) system of lifts and trains that can greatly reduce the aerobic difficulty of the ride if you are so inclined. The only downsides are that Swiss also means expensive, and the riding season is too short because it's high alpine territory.
Trail is marked as route #631. This trail is more remote offering more solitude compared to some of the other routes on the southeast face of the mountain overlooking Davos. It passes through a particularly beautiful alpine valley before climbing over the 2117 m (6950 ft) Duranna Pass. There's a small alpine lake (the Grünsee; Green Lake) on the pass if it's a hot day and you want to take a bath.
If you're staying in Davos, your accommodation likely comes with the Davos-Klosters pass which allows you to ride many of the lifts and use the local trains freely (including the Parsennbahn funicular railroad). You'll still have to buy an appropriate ticket for the bike though.
On the way down from the Duranna Pass (just after the 15-mile mark), the loop turns right off of the forest road onto a singletrack. It will be easy to miss the sign if you are going too fast, so be aware that it is coming.
From Davos, make your way to the Parsennbahn funicular railroad valley station which is near the Davos-Dorf train station. Take the Parsennbahn to the uppermost station to near the Weissfluhjoch peak. There is another gondola that goes up to the actual Weissfluhjoch peak, but you can't take bikes there. In any case, the view of Davos, the Davosersee Lake, the Landwasser Valley, and the mountains beyond when you exit the Parsennbahn upper station is spectacular.
Once you've recovered from the view, take the Parsenn to Strelapass
trail. Follow the gravel road exiting the station around behind the Parsennbahn upper station until you reach a small maintenance building. Then turn back towards the south and follow a singletrack that descends steeply through the scree.
From this singletrack, you'll enjoy a view of a beautiful valley including a preview of the trail ahead. This scree singletrack joins a path cut into the side of the Schiahorn mountain. The path is fairly wide, but you wouldn't want to fall off the side! Soon after finishing the path that is cut into the side of the mountain, you'll reach the Strelapass where there is a major trail junction as well as a restaurant.
From Strelapass, you'll drop into the Haputertällibach Valley on a steep earthen-base singletrack with lots of hairpins. Beware as part of the trail was washed out. Ford or cross the small bridge over the Haputertällibach creek at the bottom of this descent. Then you'll follow a relatively level singletrack just above the Haputertällibach creek for a little less than a mile. After that, the trail becomes a doubletrack which descends steeply most of the way down to the village of Langwies.
From there, the Langwies to Strassberg
forest road climbs steeply through some pastoral farmland. The other end of this segment is in the bucolic hamlet of Strassberg, which is watched over by fire hydrants masquerading as little elves. Or little elves masquerading as fire hydrants?
There's a restaurant with a deck that offers a sweeping view of the whole valley and a well-earned, hearty meal and appropriate beverage as a reward for the 600 m (1800 ft) that you've just climbed from Langwies. You'll want to fuel up because there is more climbing before you reach the pass.
Leaving Strassberg, the elves are replaced by cows. The first mile or so is on doubletrack passing several farms and pastures. Once the trail becomes singletrack after the last farm, 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 Grünsee (Green Lake).
From the pass, 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, ending at the Berghütte Chesetta (mountain hut). Then it follows the Schwendiweg forest road down to the Berghaus Schifer.
From there, the Klosters Overlook
forest road travels mostly through a dense forest back to the Cavadürli train station. It does have some steep climbs and descents to get your attention. Past Cavadürli, the trail parallels the train tracks most of the way into Davos-Laret station, so you may have the train to keep you company.
The following Davos-Laret to Davos-Wolfgang
segment is more difficult than you would expect, climbing steeply through a forest before reaching Davos-Wolfgang station. From there, take a short connector to the Prätigauerstrasse Bikeway
which parallels the Davosersee most of the way back to Davos.