My coach has me train on a 42x18. It's an easy spinning gear for the flats and harder on the uphills. If you were to have a bike that had only one gear, you should chose the gear that would allow you to ride in all terrain.

If you want a better cadance, ride downhill without resisting with your legs. Also try sprinting on level groud with a low gear while trying to maintain the sprint for as long as possible; after 30 seconds sit and maintain the cadance for as long as possible.

I've been winning cat 3 crits with junior gearing (max gear= 42x18 /100 gear inches) cadance is what makes you go fast.

Watch your knees, If you're new at riding fixed, the muscles and tendons that support your kneecap aren't used to the constant rapid motion. If you mash on hills, your knees will get upset with you.

I can't gear me fixie higher than 42x16 because the hills irritate my knees even after a year's use. It's becase Kansas city has quite a few short, STEEP hills scattered about.

Stay fixed and have fun