Southeast of Zurich and east of Davos, there is an excellent 8km singletrack following Fluelabach from Tschgen near Fluelapass back down to Davos.
While you could ride the Fluelapassstrasse road up to the high point and then cruise back down, there is also an hourly bus heading up the pass to Tschgen that has many stops. Most of the buses have bike racks on the back.
To reach this area from Zurich, head southeast on Route A3 to Landquart, and then southeast on Route 28 into Davos.
Overall, Fluelabach is the 23rd most popular mountain bike trail of all 31 mountain biking rides in Switzerland.