That picture looks like Spanish Steps. That's on the other side of the park from where most of the good trails are located. Did you cross over the stream? That could explain only seeing 1 mtb
Traveled up from Ceres today and had a blast. For the most part I thought the trails were is great shape. There were a couple bad spots, but not many. Hats off to the crew who maintains. Very fun.
I have some strava rides that show most of the park. They are "Jorba 2012 start loop", "looper" and "Parktour"
http://app.strava.com/segments/2557878
http://app.strava.com/segments/2239645
http://app.strava.com/segments/1831039
http://bogeysclubandcafe.com/ This is a link to the golf course and cafe the surrounds the trails. We have the okay to park there and the cafe welcomes any riders who want to grab a bite to eat.