If you're going to run just one gear it might as well be the very best you can get, a Chris King cog. Our stainless steel cogs are bead-blasted following heat-treating with sizes ranging from a leg-searing 12t through a sit-and-spin 20t.
12t = 18g
13t = 22g
14t = 25g
15t = 28g
16t = 30g
17t = 35g
18t = 42g
19t = 48g
20t = 52g