I really want to get into fixed-gear culture, but in places I consider as home there are a lot of mountains, so I use a coaster hub (with breaks!) a-la Torpedo. Having a 2.0 ratio on 622 rim (this is 27" or 28" depends on tires) gives me an ability to ride all those mountains but when I go for long trips on flat road without ups and downs I use a significantly higher gear.