The Park Ridge trailhead has a small parking area immediately off of South Bay Blvd. The parking lot is a bit rough, so I wouldn't recommend cars with low ground clearance. There is a Park Map and information station at the head of the trail that you can reference before riding.
The first half of the trail is basically a fire road. There is a 1/4-mile climb after a nice flat and small downhill section. There will be a fork in the road off to the right partway up this hill, this leads to the Crespi Trail which weaves through oaks and has more technical sections. Stay straight on the trail until you reach the high point where there is a 4-way intersection of the Park Ridge Trail and the Canet Trail
. Continue straight to stay on the Park Ridge Trail. Nice easy downhill followed immediately by riding back up to the Quarry Trail
. This is the end of the Park Ridge Trail. You can loop back to the parking lot a number of ways from here.