I'm moving to the city from SoCal in a month. I'll be living in Noe Valley and riding (up Mission I think) to work every day (and most other places in the city too). Is there anything I should know about riding in the city that is unusual or different that I might not normally know? Can anyone think of any gear or other add-ons that I should get for my bike? I've got a pretty bare bones set-up (lights & lock) and am planning on installing a rain guard for my rear tire (I don't know what it is called)...