The closest thing I have to a single speed is my 3 speed, which is geared low. We have too many days with strong south winds for me to go single speed. My evening commute today was 13.75 miles of 30 mph headwind. I used my middle gear, which is about 50 gear inches, for most of the commute. On days with lighter wind, I cruise in high gear, which is only about 70 gear inches on my bike. This morning's commute was with a lovely tailwind, so I almost wished I had a higher 4th gear.