Your friend’s solution is to get a triple crankset, a mtb rear derailleur and a little wider range freewheel, like a 13-28.
Your best bet is finding a mtb triple with a 24-34-46, or something like that. My brother is running a Shimano 22-32-42 crank, (which would work with Suntour), on his road bike and doesn’t need a cassette with enormous cogs.
With a square taper BB you can fit almost anything and a mtb rear derailleur can give you the chain wrap for a triple. I put a mtb triple on my wife’s old Univega.
It will take some figuring, but your friend will end up with a bike that he can ride for decades, not just until he needs even lower gears.
John
Last edited by 70sSanO; 06-21-21 at 07:55 AM.