We found a trail description in Ride. The first part was quite green, some of the trails were so overgrown, we decided not to ride them. The trails after the second ascend was on the other hand great.
Around the Bergsee (Mountain Lake), it's a bit far stretched to call it a mountain lake... anyway, there are many park possibilities. Although, those can fill up pretty good during the day, since it's a beloved recreation area.
Oh, and the internet connections up there is abysmal. So if you like to load the trails on the Garmin, do it beforehand.