Jimmy McCaffrey posted the route:
The East Bay Skyline National Trail traverses the ridge line above the coastal mountains situated to the east of Richmond, Berkeley and Oakland; and ends in Castro Valley. It goes entirely through the East Bay Regional Park system; Wildcat Canyon, Tilden, Sibley, Huckleberry, Redwood and the two Chabot parks. This is the eastern portion of the yet-to-be-completed Bay Area Ridge Trail.
I believe it's marked so that hikers can use either the French Trail route or the West Ridge route through Redwood Regional Park. I however think that the up-and-down of the French Trail (the "crown jewel" of East Bay trails, imho) along with its beautiful single-track (as well as being closed to bikes) adds some challenge to the 32+ miles.
The northern terminus is Wildcat Canyon Staging Area in Wildcat Canyon Regional Park, on Park Ave in Richmond, where there’s a short paved road that ends at the Wildcat Creek Trailhead. There are three potable water sources available; the first at Tilden Steam Trains, the second at Sibley Staging Area and the last at Skyline Gate.
Trails and mileages:
Wildcat Creek .44 to Belgum
Belgum 1.00 to San Pablo Ridge
San Pablo Ridge 1.28 to Nimitz Way
Nimitz Way 4.72 to Curran
Curran .27 to Sea View
Sea View 2.18 to Vollmer Peak
Vollmer Peak ~.55 to Lomas Cantadas (water)
Lomas Cantadas 2.55 to Old Tunnel Staging Area
OTSA .87 to Sibley Staging Area (water)
Sibley SA 2.76 to East Ridge
East Ridge .20 to Skyline Gate (water)
Skyline Gate .56 to French Trail (via West Ridge)
French Trail 4.04 to Orchard
Orchard .18 to West Ridge
West Ridge .62 to Golden Spike
Golden Spike .78 to Big Bear Staging Area
BBSA .25 to MacDonald
MacDonald 2.52 to Grass Valley
Grass Valley 1.48 to Brandon
Brandon 5.36 to Proctor Staging Area
Approximate distance: 32.61 miles
I've only been able to find available info from a few thru-hikers through their websites; here's one: gurmeet.net/hiking/hikes/East_Bay_Skyline_National_Recreation_Trail.html
I feel this trail is an under-rated, yet iconic gem of the East Bay (and Northern coastal California for that matter); both the Dick Collins Firetrails 50-miler and the Skyline 50k are two classic East Bay races that both use large (southern) portions of the trail.