Here's a crappy screenshot of me climbing the Corkscrew Wall near Foresthill yesterday. This is definitely geared bike territory. It's a 4.1 mile climb, 9.2% average grade (18% max), and 2,033' of climbing. After that climb, you get to climb back out of the canyon on Mosquito Ridge Road for 10 miles. That climb probably could be done on a SS, but I don't think I'd want to do it for 10 miles. Spinning on long climbs is still more efficient.
The smudge on the left side of the camera is from a bug that hit my riding partner's camera lens during the Mosquito Ridge Road descent.
Here's video of the Corkscrew Wall climb (caution heavy breathing!). It alternates between my riding partner's footage and mine. I showed us climbing similar areas, so you get to see how much I suck compared to him (he finished the climb about 20 minutes before me).