Freewheel replacement for a touring tandem bike
I think in this situation, to avoid an &quot;upgrade spiral&quot;, you will be better off changing your chainrings. Chainrings are not overly expensive and probably won't require new derailleurs or shifters.
I have been known to take apart freewheels and change the cogs. I've even re-spaced them or changed the numbers of speeds. But if you want an overall lower gear, you should probably change your chainrings.