From what I understand, those trails were properly designed within IMBA's sustainable trail standards. With that in mind, I called it what I saw it as, a skid rut. Also, could you please explain why the trail widens out so much near that softball-sized rock near the bottom of the rut? Would it be that such a minor obstacle warrants veering so far off the line that it would double the width of the singletrack? Don't most people ride full-suspension bikes in the dirt around here?