All I can say is get in shape like you are going to fight Rocky. I prepared for this by eating a chili dog. Big mistake. 18 miles of constant uphill battle climbing 4000 feet. Teasing you with a small downhill every once in a while, just enough to make you think it isn't as tough as you were thinking a moment ago. Then lets say you were able to power through and make it to the top, that 4000 feet it took you to climb 18 miles, now you are going to do that down in 5 miles. Steep, switchbacks, roots, and drops. You could lock up your back break and just slide down this if you wanted. One word, Gnarly.