Two years after I finished racing and most of my rides were on my fix gear, I used to do crazy rides up Oakland's Jauquim Miller, turn around at Skyline Blvd and bomb down the 1000' back to Oakland. I never saw my speed, but I was never passed on the 4 lane parkway with median that was usually driven at 50. All on a 42-17 . . .
Awesome. Ever go through the Caldecott Tunnel on a bike? I used to commute to Berkeley from the East Bay, and I was sorely tempted to try it on several occasions late at night, to avoid the 1000 foot climb over the Oakland hills over Fish Ranch Rd / Claremont. Heading east, the tunnel is all downhill, so it seems quite do-able.