It’s single speed season.

If you’ve got  vertical drop-outs, you’ll have to convert your road bike; you’ll need a single speed chain tensioner like the Paul Comp Melvin pictured on the left [there are dozens on the market - Paul Comp stuff is extra groovy].

One cog and spacer(s) will turn your cassette body into a single  single speed as shown in the inset detail.

You’ll want to use enough spacers [behind & in front of the cog] so the chain lines up perfectly in the same plane as the chain-ring.

You’ll also want an 81″ gear [see gear chart].

A 39 tooth chain ring and a 13 tooth cog gives you an 81 inch gear.

Visit gearcalc.htm for a gear chart that includes inches for a 53 tooth chain ring.