I know every inch of that trail.
We have a cottage on Black Lake and have had the use of the trais on Black Mountain essentially to ourselves for many years. 30+ miles of trails, lots of good climbing, many ride options and beautiful forrests. We rarely see anyone on the trail. Sound too good to be true? It is becomming so.
Lately, local horseback riders have discovered the trails and use a portion of the main loops regularly. With all the sand up there, they really screw things up. Some days, the hoof marks are so bad it feel like riding down long flights of stairs on a rigid frame.
There has also been some logging activity in the last year and it is continuing this Spring. There are huge ruts in those areas from the skidders.
Needless to say, what was, until recently, our perfect trail system, is now more a matter of heading out there to see what is rideable. That said, it still is fun and a majority of the trail is still good.
There shold be a map on the Black Mountain trail guide site. I would be happy to suggest loops and "secret spots" to avoid the above problems. Also, my wife and I are up there most weekends in the summer and could give you a tour if you are up when we are.