Maintained by the BONC, this is a fun sweeping singletrack with a couple of tight switchbacks going from Round Mountain and Traihead (top) to the South Yuba Trail: Edwards Crossing to Purdon Crossing (bottom). From there it is possible to turn left towards Pudron Bridge (easier) or right towards Edwards Crossing (technical).
It has a very smooth surface most of the way with very few rocks and roots. It can be covered with leaves or pine needles, depending on exposure and time of year. The Bicyclists of Nevada County club will make sure that the fallen trees are removed after the winter but watch for unexpected obstacles.
Riding uphill is a good workout, with steep sections separated by easier sections at a lower grade, for recovery.