The unpaved bits where they tore up the track but left the rock are 'challenging' to ride. Even for an experienced off road rider. The best I ever managed was

The unpaved bits where they tore up the track but left the rock are 'challenging' to ride. Even for an experienced off road rider. The best I ever managed was about 2 miles of it. The paved bits you can go for a decently long time. Just be aware some portions are 10-20 miles with nothing really in between but farm fields, so plan accordingly.