Probably the best MTB tour in the region.
Buy a day pass at the Rothornbahn in Lenzerheide and get to the very top (Rothorn, 2800m). From there you take the trail on the right. At the beginning it's wide and easy, then it becomes a technical singletrack down to 2100 meter.
Now take averything off that makes you sweat, because you will have to push your biker 500 vertical meters up. There are three small passes.
The first one:
The second one:
The descent of the second one has a very steep bit where you will need to push your bike. After that the downhill is quite fun:
Finally, you'll reach the Furcletta Ramoz, where the real epic descent begins.
We found a joint up there, but we didn't have a lighter...
The valley where the trail goes:
The trail is not hard. It's superlong and very fun to ride to Arosa.
In Arosa you'll take the Hörnlibahn and then the next one to the Urdenfürrgli.
From there it's all downhill to Lenzerheide. Long, lots of corners and nice views. At the end you'll follow a track of the bike park.
The vertical meters include the cable car from Arosa. Real effort: 700 vertical meters.