Kathy, Lindsey and I were headed on our bikes out towards the beach (and the Yves Saint Laurent exhibit at the de Young Museum) when Lindsey announced troubled gears that needed attention. We planned a detour to one of the shops on Stanyon until we nearly rode into Bikeman Ben set up mid-panhandle for just this kind of crisis.
Lindsey explained the problem, and Ben also fixed about 3 other things on her bike for just a small fee.
This sort of thing makes me love San Francisco even more (if that's possible).
No one wore anything fashionable, but you can reach Ben for your mobile bike repair needs at bikemanben at gmail dot com.