when you get to the top(cocktail rock) roughly six-seven miles,there is a fork(most people turn around here)if you take the left(i think is old san juan) follow the trail(2-3 miles) to the T interseccin,thats new san juan.you take a right and stay right at the 2 spurs to the left(thats the chiquito trail,thats another story for a another day,is an awesome trail as well) you are going to comeback to the fork,take it straight lower your seat and enjoy the awsome downhill! that should give you about 16-18 mile round trip.i think it was about a 3hour ride last time i did't that way somewhere in there,taking a couple nice breaks to enjoy the view,you gotta do that at san juan, what a place! enjoy buddy.