I have a 2020 Electra Cruiser 1 and just picked up a NOS three speed Nexus hub/shifter. It came with everything but the cog. Can I use my existing 22T cog and single speed chain? I was thinking about going to a 20T or even 19T as I live in FL and this will be for just some neighborhood/MUP all flat type riding. Anything else I need to be aware of to install? I'll be having my shop do it and hope it's not too complicated.

Thanks for any input.