Lots of different terrain - at the beggining, it's nice dirt, tires dig in nicely, then there are some big rock slides that are very hard to ride over, then at about 6 mi. lots of big rocks imbedded in ground - very bumpy. don't know what's after that.
How to get there:
Next to Napa in Palmer, there is a dirt parking lot - take the trail from there and keep going straight. you should see the railroad track from time to time imbedded in the dirt.