The Nate Harrison grade is nothing more than a dirt road with a lot of switchbacks. It will take you all of 15 min to drive up that hill. Depending on what day and time you go, there may be a lot of mountain bikers riding that road that will all go ape ***** over the dust your kicking up, and if your sliding around those corners (very fun by the way) you might even get called in to the sheriff, who will be waiting at the top or bottom for you. If I was you, I would head out to ocotillo wells for some night fun. It's probably well over 100 deg. in the day now isn't it? More trails, and less chance of killing mountain bikers. Is Los Coyotes still open? I miss that place. Lots of challenges in there.