As a weekend morning bike commuter, I sometimes get surprised by a marathon or fun run blocking my commute.  Is there a listserve or Web site I can check? 

The San Francisco Bike Coalition tells me,

“Unfortunately, I don’t know of a resource like that that is public.  There is a regular email sent out from the Parks Dept but I’m not sure if they send it to individuals - my understanding is that is is mostly an organizational outreach piece. Perhaps if you ask their press/communication dept they’ll make it public? Good luck!”

Thank you,
Hein