I don't know the numbers for this year, but I was last in San Francisco in 2009, and cycling seems to have increased dramatically by my eyeball estimates, and by some reports as well. Certainly there were bikes everywhere, on the road and locked to racks and meters. Here are a couple of shots; more will show up in a week or two when I've had time to process the images. Bike racks like these are everywhere, and heavily used; there are plenty of single racks as well.
On Market Street on a cold drizzly day
At the Ferry Building, on a cold rainy morning
Even when the drizzle turned into a hard steady rain, folks were riding blithely along on their bicycles (and scooters and motorcycles), a phenomenon I've noted as far back as ten years ago.
The difference is, most of them don't look like enthusiasts now, but regular working people, office workers, folks who would otherwise be driving but who have discovered a better way. I think there was a lot of latent desire to start living outside the (metal) box, and SF's diligent buildout of bike infrastructure in the last few years simply made it easier for the timid to start riding.
The multitude of bike racks alone would be enough, but the bike lanes I've seen here are the excellent, far better than anything we have in LA. Except maybe the ones on Santa Monica, which I'll be riding in an hour or so myself...