How did you find the 16T sprocket? If you are good with it, use it again. If your tired of fighting wind and don't mind a slightly higher cadence, go with the 18T sprocket. Lower gears can be more efficient against wind and climbing.
That said most people that buy these bikes aren't terribly concerned about efficiency anyway, And while fighting wind is harder with a higher gear, As long as we don't put too much pressure on our knees, Many folks ride one speed bikes for many years without any problems.
On my 21 speed comfort bike on flat land my 62 gear inch sprockets are in between the 55 and 70 GI I use on most rides. If I choose one it would be 62. 70 GI is too tall for going against the wind on a regular basis. But that's just me, Comfort is more important to me then speed and the right gear is a an important part of making my ride a pleasure rather then a chore.
I do like the simplicity of a single speed bike, But I prefer at least the 3 speeds available on an internal hub, that might have worked for me now, Just like it did when I was 13 years old. Actualy that 3 speed was the most fun bike I ever had with a gear for climbing, fast cruising, and normal riding with no derailleurs to deal with.
Last edited by xroadcharlie; 06-22-20 at 03:46 AM.