We really love biking and especially biking in nature, on unpaved roads. For me as much adrenalin as possible, for Monika somewhere in the middle, still on the safe side. This is our favourite spot in Czech Republic, up north close to the triborder with Germany and Poland. 
There is unspoiled wild nature, excellent systems of trails on 4 grade difficulty levels – green, blue, red and black, exactly the same as you got on ski-slopes. Trails were designed by big guru of trail racing reborn – Welshman Dafydd Davis, they have quite nice flow and there is one for every age and level. They even extend across the border to Poland.
There are now two trailhead facilities, which are essential to the whole place. You can have a beer and warm meal there, have a shower after long muddy day, you can rent decent range trail bikes, all the time perfectly prepared. From entry models to fully suspended bikes costing around and over 70,000 CZK. The rental fee is quite decent, for me it’s obvious choice not to have own trail bike for only few days of usage, no need to clean and transport it in the car.
So voilà there is a video of me enjoying the rides there.