I am riding a 37x16 on the 24" with a 24x1.75 Tioga power block which gives as ratio of 55.54.
The 20" was with a Tioga powerblocks 20x1.60 and a gearing of 44x16 which gave a ratio of 53.59 which was much lower and explains why I was so tired racing he other week.
I am now changing to a 20x1.75 powerblock on the rear and changing the gearing to 42x15 to give a ratio slightly higher than the 24" at 55.78 which is as close as I can get it I think.
As I said I have bought a new powerblock folding 20x1.75 tyre and a new box 15 tooth sprocket. I already have a rental 42 chain ring that I will use for now although I have a new rennen 42 tooth chain ring in the post as I prefer the look of them to the rental chain rings.
I also bought a bunch of inner tubes to re-stock my parts box.
Here are before and after photos:




