that's so awesome.
Good NPR article on the San Francisco one. Looks like a big production with camera crew (was turned it into a Android commercial). His had many stair-steps, 27 miles. I'm thinking shorter, using diagonals, and of course broadcast on MassUp.
I think I've done what can be done with Northside options.
There are 8, 14 and 19 miles variations. The smallest looses form, and the large one requires some big non-bike streets. Leaving the middle one (blue), which still one might not recognize unless told. This took hours, due to one-ways, and trying to imply the angles and curves. I also reviewed other orientation options. I'm going to call this done, for a future northside mass.
Use the live Google Maps version at http://goo.gl/maps/sSp7Z
Cool idea, but why limit yourself? Consider kidneys, livers, or really go crazy with intestines.