The Pig Iron Loop, marked as red, is an intermediate level trail. It starts and ends near the Folsom Bridge. Riding clockwise, the climb to the top of the ridge is 1.5 miles of winding textured singletrack. Once atop the ridge, you catch your breath along the north spur of Shades Mountain on a smooth wide trail.
Once you reach the four way intersection, take a hard right and let loose on a fast smooth decent. Follow the red arrows all the way back down to Folsom Bridge. Riding counter clockwise, the trail starts off with a short steep climb to the top of the ridge.
After crossing the top of the ridge, the downhill is not as steep, but has a longer steady winding decent back to Folsom Bridge with a fair share of fun switchbacks.