I'm not all together certain. It was my 26th birthday yesterday and I went for a bike ride on the old singlespeed. It was the first time I took it out since I broke my thumb with it back in June. Since then it's developed a new chain and a new rear cog. I'm still riding with a 20t, but I'm using a Surly cog instead of an Endless Bike Co. one. So far, it rides exactly like it did before. The Surly cog is steel, though, and the Endless Bike one aluminum. It'll be interesting to see which lasts longer. Steel is suppose to by a significant margin.
Fall is definitely arriving soon.