42/17 is my ratio, and it works for me on the hills I come across. But the hills in Louisiana are mostly man made elevations, such as bridges, overpasses, etc. I've never done any extended riding in an area with a lot of hills.

But there are plenty of fixed gears in San Francisco and Austin, both pretty hilly, so you'll be fine. You might just have to do a little more out of the saddle climbing than you would on your road bike.