And these are only the ones that get reported.
Where are bike poachers most active in San Francisco? For an answer, try scanning this enlightening map from data outfit Seismograph: It shows the 813 reported bicycle thefts of 2013 laid out as angry-red blotches (much like the ones on your face the last time this happened to you).
Smaller circles represent one purloined bike; the concentric, target-looking circles show the sites of multiple thefts. Write the folks at Seismograph (motto: "To be honest, we're not entirely sure what Seismograph is yet"):
The trends are somewhat as expected. Market Street between 6th and 4th, the Ferry Building, CCSF, 16th and Mission BART and the general hospital are all popular spots for bike theft. Nonetheless, I still found the dataset interesting.
The largest grouping of thefts, around the Powell Street BART, makes sense: It's a hub of commuter and tourist activity where stealing might be lost in the bustle of the crowd. (It's also near a large, open-air drug market, which may or may not influence the numbers of bikes going AWOL.) And the preponderance of stealing in the Mission likely has something to do with the neighborhood's bike-loving populace: walking there at times can be like navigating through a highly fashion-conscious velodrome.
Seismograph has also put together a crude timeline of bike thefts based on the police statements of the unwillingly bike-deprived:
The San Francisco Bicycle Coalition estimates that a bike is stolen in the city every three hours, which if accurate would represent a much larger theft rate than what's represented in the 2013 data. The local police are well aware of the problem. They run a responsive Twitter account that asks people to send pictures of their missing rides. And this year, they're experimenting with putting "bait bikes" of various conditions around town; when thieves take one, hidden GPS trackers and RFID tags lead a trail to their doorstep. The cops say this effort has led to several arrests.
Anyone worried about having their bike ganked can also indulge in the police department's psychological-warfare campaign: It's flooding the city with thousands of stickers that read, "Is This A Bait Bike?" Head to any district station to get one, then slap it on your frame and have fun messing with the heads of would-be thieves.