Partially paved and partially gravel, the trek up Petty Creek Road is great for bike touring and gravel riding. When you are riding away from the river, the route is mostly uphill (very gradual, though), and it's an easy, fast descent back down to the river.
Once you get to the very top of Petty Creek Road, there are a few different forest roads you could turn onto. If you want to extend your ride, you can combine some of the other roads to make different loops.