Busiek was around before Sac River and has a lot of history despite being a simple trail system. Some tough climbs and technical downhills, but mostly it's flat and fast. Go when it's dry, but in late summer some trails will be overgrown. Still, Busiek gets plenty of mountain bike use and was mentioned in an article by Bike Magazine in 1998. You may have to cross a stream or two. There are some clear maps displayed at the trailhead: the west side is the best for a solo ride, the east side is good for stoners. There is a shooting range and a graveyard too, but don't let the gunfire scare you, it's normal.
If you are a monster do the Busiek-Chadwick-Swan Creek-Chadwick-Busiek Marathon loop, and then do it in December like my buddies and I did back in '96. Two words: frozen toes. Watch out for the puppy mills. That epic definetly gets a head-knock from me.