"The Wall" at Mt. Diablo. I made the mistake of going right after it for my first try some years ago. I wound up making mini switchbacks and found myself in the gravel shoulder, spinning out my rear wheel and going down hard. Since then, I catch my breath at the lower parking lot before "burning the matchbook" to the summit.
Although, I think the toughest part of Mt. Diablo is the stretch preceding the hairpin turn at Devils Elbow, one of the last switchbacks before The Wall. The road in this section faces Morgan Territory to the east and is completely exposed, but shielded from cooler breezes from the west.
The summit steps overlooking Morgan Territory. The visitor center, by the way, is air conditioned and has ice cream.
This week's ride, however, coincided with one of those rare SF days when it's equally gorgeous at the Great Highway at the western end, where I successfully reclaimed my wheelsucker title.
It was a perfect City-ride day. We did a new route for me, returning counter clockwise from the beach through Daly City, Colma, over San Bruno Mountain, then back up around Candlestick to China Basin.
[Aside: Funny thing is, while in Colma, we rode past my first SF apartment. It was an in-law, a hook-up from old hip-hop connections. The owner's son once managed Mix Master Mike (ISP, Beastie Boys). A recurring phone conversation went like this: "Mike's here." Mix Master? Nah. Mike. He's a writer. Not a graffiti writer. A writer. Magazines. Newspapers." Oh.]
Bless the Yellowjackets. My chain snapped just 200 yards from the end of the ride, close to BART. And a few riders turned back around to make sure I was okay. ... I'd been thinking a lot about those things specific to the Bay Area that make the high cost worth it. Those institutions that might not exist in other cities. The Yellowjackets are one of those institutions.