The mountain bike legal part of this trail serves as a connector between trails in the Shell Ridge Open Space. It starts at Briones to Mt. Diablo Trail
and goes westward, up and down over ridges. The legal bike route ends when a singletrack goes off to the left and the fire road continues for a brief while as Franco Ranch Loop.
The trail makes lots of turns that are not obvious. You'll need to check the signposts and map at each intersection to make sure I stayed on the trail.
Note: The Sugarloaf to Shell Ridge Trail
consists of three parts. The part the goes from Sugarloaf Regional Park to the entrance to Shell Ridge Regional park is a paved bike path and is not included in this description. The second part is a singletrack section at the end of Stewart Ave in Walnut Creek that is also not bike legal and therefore not included in this description. The third part of the trail is described here going in reverse (since that is the only legal way to start it).