Park at Phipps/Diamond X parking lot next to the railroad bridge that crosses Molt Road.
To access this loop, you'll use the Upper Loop Connector which is a very steep climb, an excellent test of fitness. Once on top, turn right on the singletrack, the trail flows better counterclockwise around the butte. The trail on the north side of the butte is one of the original local Black Diamond trails. Over the years, it has broken-in to be easier, but it is still extremely fun!!!
When added to the lower IMBA singletrack, this makes an excellent 1-hour "Lunch Loop!" See the Phipps Park featured ride for more details.