I thought I could use a chain tensioner?
for single speed yes but for fixed no.
But would it look ok or just plain silly?
Look at any pictures of bikes with Marys on and decide for yourself – its subjective. Personally I’ve got a bike that I did pretty much the same thing with – flat powdercoat grey, single speed with a shiny stainless chain, no graphics, rigid exotic forks – the shortest I could get -, brown fat alberts. I ditched the disks and went back to V brakes because I had them and because I think they look nicer. I stopped short of swept back bars and a big sprung seat becuase thats a ‘look’ that I associate with much slacker angled bikes. Big wide sprung saddles are for bikes you sit up and back on, if you look at people riding dutch bikes they are pretty much in a standing reading the paper position rather than a hunched MTB position – the narrow saddles we use are because our weight is on our hands not our arses. That kind of bar and saddle are for much shorter top tubes and slacker head and seat angles
So I stuck with a conventional bar and saddle – sort of a big bmx