Golspie is good for that sort of thing. I must admit its a nice ride during the week Golspie, when no ones around.
Again I suppose I haven't been for a few years and there are some newer tracks venturing further up the coast, but it was good for a couple of hours out where you knew what you were getting. I am not a trail park person but its always good fun to ride these trails. The black one is quite rocky and very steep up the top near the monument section but the rest is doable on a rigid singlespeed. Its a steep, long. long climb straight out the carpark but it winds its way up. Hard but certainly nice and far better than some of these places with forestry road for climbs.
Jamie