My search skills have failed me .
I'm trying to find out if anyone makes an adapter or "spider" to use an inner chainring as a singlespeed cog on a Shimano cassette body / freehub. I understand that the usual solution is to run a smaller ring in front, but there is a minimum size I can use in front and still clear the brake. I could hack up an old cassette, but it would be nice to have a cleaner solution for using larger cogs.
My current setup 34x24 is functional, but I'd like a bit lower gearing for steep sections that I now have to walk.
This may be one of those stupid questions, thanks for humoring me .