There was a question in another topic about shorter routes for this ride.
I just quickly mapped out a couple of possible options for shorter loops.
The main route is about 56 miles, 5600'.
http://www.bikely.com/maps/bike-path...Kings-Mtn-Loop
If you take Page Mill down off of Skyline to Altamont and that back to Foothill, it looks like 33 miles, 4800'.
http://www.bikely.com/maps/bike-path...Page-Mill-loop
If you cut off of 9 at Redwood Gulch, you can take that to Stevens Canyon and take that back to the start.
18 miles, 3000'.
http://www.bikely.com/maps/bike-path...Stevens-Canyon