[I approached from the right side of pic, the West face: source WikiCommons]
Today was my idea of perfect. At the end of 6 hours of rigorous and gorgeous trail riding I can kick-back without the bike monkey on my back.
Mount Diablo is most well known for the amazing view from the top. On a clear day one can see the huge San Francisco bay, islands off-shore to the West, Yosemite East, and tons of Bay-area cityscape.
[Frog's Pond in remote region below the S. face of summit]
The weather was sunny 60's with a cool ocean breeze. I saw less wildlife since I was keeping a good pace, but managed to run a turkey off the road and watch a coyote pester prairie dogs.
[A natural rock slide used by kids at "Rock City"]
I didn't keep track of mileage, my heart rate, or GPS coordinates. I estimate that I climbed around 7,000' since the peak is nearly 4,000 and I went over a ridge at 3,300' and down into the foothills on the opposite side before ascending to the summit(which involved pushing my bike up steep lose rock).
To get to Diablo S.P. and back I rode 25miles? on wonderful bike paths (path= totally separate from road) leaving right from Heather's family's house. It's like a little Portland :-)