I disagree w/ 53-11. I tried that when I started and its not the same. At least if you are going fixed. Fixed pedals don't stop to coast and the momentum works with you, so what seems like a tough hill on a free wheel seems much easier to me on a fixed (given the same ratio) since the momentum helps me continue to pedal. Plus, after a pretty short amount of time of riding fixed, your stronger legs will get you up hills easier than you ever did before. I FLY over the bridge that used to kill me when I did it in an easier gear on my 10 speed back in the day.

At least that was my experience.