This is one of my favorite mountain biking trails however it is also a great hiking trail. To hike Cox Hill head directly from Dawson Campground just watch out for bikers flying down. The easiest way to bike up is to follow the gravel road from the Campground. To just hit the summit of Cox Hill you can take the shorter route up Jumpingpound Ridge Trail. To visit both Cox Hill and Jumpingpound Mountain/Ridge you can take the longer route up Jumpingpound Summit Trail (my preference). Once you get up all the switchbacks on Jumpingpound Summit trail you are rewarded with great views and wildflowers depending on the time of the year. You have the choice of visiting the Summit or you can ride Jumpingpound ridge.
There is some decent downhill towards Cox Hill however you will need to gain this elevation back up to its summit. This downhill from the summit of Cox Hill is some of the best downhill mountain biking I have done. Expect rocks, roots, ruts and sharp turns. Your brakes will burn just as much as your fingers when you get down.