From Ari Feinsmith of the Silicon Valley Bicycle Coalition (SVBC):

Our volunteer mechanics will perform basic maintenance and repairs to your bike and will teach you along the way. This event is almost full. If you want to bring your bike to get fixed but the event is full, let me know and I'll try to find a way to get you in. If you can help as a bike mechanic, please sign up here. If you don't have experience but want to help, I can pair you up with a mechanic who does.

Plaza del Sol, where the event is located, is across the street from the Sunnyvale Caltrain station.  It's also served by VTA's 55 local and 523 Rapid bus lines.