The trail starts up the southwest ridge of Bachelor Mountain on a nice trail through a fir forest. When you switchback and come out of it after about a quarter mile and 200 feet of elevation gain, it again follows the SW ridge up through an area filled with low manzanita, kinnickinnic and blueberries. As you climb you will come to a gentle saddle where a south ridge comes up just about a mile into the trail and 600 feet up from the trailhead. In the flat area where these ridges meet you will come into an area of young trees and grey snags from the Buck Mountain Burn in the 70's. Great views of Jefferson and the Cascade volcanoes can be see from here.
Continue on up the ridge on the trail another tenth or two tenths of a mile to a junction. The right fork (or it appears to just go straight here) goes to Bruno Meadows and is signed. The trail to the left is the route to the summit of Bachelor Mountain. There is a sign but currently it is resting on the ground against a tree. It's another .9 miles and a couple switchbacks up this trail to the summit.
Descend the same route. Total length is about 2 miles and 1100 feet of elevation gain.