Oak Ridge Tr688A is a steep switchback trail, normally only ridden as part of the Surveyors Rdg Tr688 loop. An alternate loop is described below.
The 2.2mi Oak Ridge Tr688A (~1850') descent contains switchbacks with large loose rocks, erosion and banking, and is not suitable for climbing.
A hike-a-bike to the top, then downhill is certainly an option, but the described CW loop is not much tougher than hiking and includes a Bald Butte climb on Surveyors Ridge Tr688 so adds some variety.
Using FR17 to shuttle to the upper Oak Ridge Tr688A TH is another option, for those seeking some fast vertical descent.
Dog Rvr Tr675 provides a longer descent and easier shuttle.
Oak Ridge Trail 688A, Surveyors Ridge Trail 688
Bottle Prairie Campground, Eightmile Crossing Campground, Fifteenmile Campground, Knebal Springs Campground, Pebble Ford Campground, Sherwood Campground
Ranking consistently applied to all of the listed trails.