Around 70 gear inches works well for me. It's pretty fast on the flats, but not too tall for hills. I live in a illy area, but I'm not sure I would prefer taller gearing in a flat area. the ability to spin at a faster cadence is a good skill to build, and one of the reasons fixed gear bikes are so good for training. Before riding fixed I tended to ppick a tall gear, and "mash" to get my speed. Taking spinning classes, and riding fixed has improved my leg speed, ability to accelerate, as well as my ability to climb in tall gears.