Mt. Diablo is an omnipresent feature of the Tri Valley. It is quite nice to have a 3800 ft high mountain in the backyard. Daily light changes paint the double-headed monster in lovely colors, severe weather makes it look really scary, and an occasional marine layer that sneaks through the 580 corridor and gets stuck in the mountain's mid section makes it look like a fourteener.
I have been to the summit and some trails on Mt. Diablo on foot and on bike several times before, but did not know too many trails there. We went to explore and called it a trail run, knowing that the uphill sections will be a fast hike, if that.
On the "back side", we decided to loop north on Bald Ridge instead of continuing to the wide and smooth Prospector's gap trail. Bald Ridge was neither bald, nor really a ridge. This was a super narrow and rocky trail perched on a rocky wall just below the summit, overgrown with thick vegetation and going up and down over spines of rocky outcroppings all the time. Its last section before the Meridian Rd was actually very pretty, lava rocks and pines, kind of like in Hawaii.