Some pics…
The start of the Strava segment from before the North Gate has about a 20 minute warmup built into it. I had ambitiously loaded the North-South-North two HC climb route.
Deer everywhere for the early birds, a buck and a doe:
and some posers on a hill:
My last attempt to climb Mt Diablo on a bike was after my buddy John and I bought MTBs in 1988 or 1989. We knew we had to do something epic, so we decided on going up Mt Diablo on the fire roads! That lasted a mile, maybe two, before our fitness and the slippery slope had us pushing the bikes uphill. After nearly getting heat exhaustion on that epic day some 33-34 years ago, we made it to this very Ranger’s station where the North and South roads meet:
Notice the overcast skies. From the ranger’s station its another 4.4 miles to the summit. After 3 miles up the road I reached the wet, cold, and windy “top of the marine layer” cloud deck:
There’s a video of the clouds moving on Strava. At this point I saw two riders in front of me, I passed one:
before the summit, and the other one I was two bikes lengths behind him on the 14-17% grades at the very top. He must of heard me huffing and puffing, as I set a 2 min power best for the last 90 days. At the end of 1x90 minutes of 85% IF. Was gassed but not wheezing yet, wanted to dismount and walk the bike up but then I couldn’t face that dude in the parking lot at the top #NoWalkOfShameForMe
Summit parking lot at 3849 feet / 1170 meters, including dude I couldn’t quite catch and pass:
He wasn’t even breathing hard when we hit the parking lot 
Xertonline gave me a breathrough:
and a commemorative Google maps pic of where I was stalking the dude right before the summit parking lot. Side note: IMHO that is the slickest feature of Xert
I was just happy to have finished the climb without stopping, and afterwards seeing almost no aerobic decoupling (1.8%) over 90 minutes of erg-like power by feel. They say erg mode keeps you honest, I like to think that long HC climbs are like a metabolic truth serum 
The first 110 minutes of the ride, and full climb, was powered by a single 90g carb bottle and light breakfast at 5am.
On a clear day you can see all the way to Mt Lassen in the north, and the Sierra mountains to the east. With binoculars you can even see Half Dome in Yosemite Valley. Today was not one of those days. However I could see Mt Hamilton (climbed it last month) on the left of center, and right of center is Mt Loma Prieta in the Santa Cruz / Coastal Mountains:
Pretty thick marine layer. Next time I’ll remember to pack my long finger gloves and a thin jacket/shell for the descent.
Fun graphs for @DarthShivious
Kinda of like doing Wright Peak 3x30-min without any rest breaks or erg (I’ve done Wright Peak -2 three times). At 85% ftp target I’d call that tempo but many would call it Sweet Spot. Good for #3 on the all-time 90-minute power bests, although a solid 31W below #1.
Elevation of the HC climb on Strava, highlighting the steepest gradient at top:
My Garmin 530 was only off by 50 feet on max elevation.
Next time I’ll do the South Gate climb. Or the elusive dual HC, North-and-South, with a return to parking at the north gate.
Happy Monday!