Bicycles and the Human Machine Ride

From SFBC:

As you prepare for your two-wheeled Bike to Work Day commute, get to know how your body powers the pedals on a pleasant ride through the Presidio. Investigate yourselves as a human machine, take a closer look at the muscles in a leg, and trace the path of a blood cell through the heart. Join Exploratorium educator Ken Finn and Discovery Street Tours leader Robin Marks on this moderately hilly 8-mile bike ride. Participants must be members of either the Exploratorium or the SF Bicycle Coalition, and are welcome to join either organization on the day of the event. This ride requires a bicycle, a helmet, and the ability to ride 8 miles in a group. Preregistration required, $20, limited to 30. Click here to register