Heading down Lost Chromosome (part of the Urban wilderness S Loop) you get to signs for Chain Ring. L.C. continues down hill to the Fork of the river area. Chain ring is the perimeter of the Helix area (on private land easement, so be on good behavior or we could loose this) and is made up of single and some double track. Some long climbs, one fairly technical where it meats the E end of AC/DC. Inside the ring are AC/DC and MCR which are grand flowy things with a few berms and fun roller coaster bridges. Also Chicken Coop which is a direct route bypassing most of ac/dc, often down the fall line. It is steep and rooty and often washed out. There's also Creek side loop out side of CR, at a nice gravel stream ford. Creek side is a short loop with a long climb.