Long but worth it
This track is really remote, so make sure someone knows where you are! We parked just before the boom gate, and it was around a 45km return, mostly along old forestry / mining roads which were in pretty good condition. There are a few tough climbs and sketchy bits of track. Also, there are at least a million snakes, maybe more. Don't ride over them, it makes them angry...
If you poke around in the bush right at the end, past the open tailings area, you can find the old mine shaft which is very impressive! Some great view of the river as you ride along the track.
Not the most exciting riding, but it's a great spot to explore, and what better way than on your bike!?