I run the dirt trails here a couple times a week, at night in the summer (with a headlamp), including the part that's labeled "MTB Trail" off to the north--it's really just a new part of the trail (but a there-and-back, not a loop; most of the rest you can do as a loop). There's a fifty foot segment at the SW end that crosses a stream on Greencastle Rd, but you can now avoid this by a new trail + footbridge that doesn't show on any maps yet; if you're coming from the SE, look for a path off to your right just after you cross the paved path. I've also XC-skied parts in the winter (golf course can also be skied). Lots of deer at dusk, occasional fox, owls. Lots of side paths for change of scene--any of the black dashed paths, not just the red path (which is someone's GPS, I guess).