BEEN WORKING ON FIGURING OUT THE GEAR RATIO SET UP BEFORE I GOT TO FAR INTO THE BUILD
AFTER GOING ON A NUMBER OF WEBSITES TO FIGURE OUT HOW TO CALCULATE COMPUND GEAR RATIO I BELIVE I HAVE FIGURED OUT WHAT WILL WORK
I USED THIS SITE TO DOUBLE CHECK MY CALCULATIONS
https://evolventdesign.com/pages/gear-ratio-calculator
FROM WHAT I HAVE DETERMINED
1ST SPROCKET WILL BE 40T
2ND SPROCKET ON TANDAM COASTER WILL BE 18T
3RD SPROCKET ON TANDAM WILL BE 48T (THE FIRE ARROWS ORIGINAL SPROCKET)
REAR SPROCKET WILL BE 39T
THAT SHOULD BE VERY CLOSE TO RUNNING A 50/18 ON A STANDARD 26" BIKE
I KNOW ITS VERY HARD TO TELL BUT THE BEARING CONE THAT THE COASTER ARM ATTACHES TO WAS A BIT TO BIG (ORIGINAL VERSION ON LOWER COASTER)
I SWAPPED A 28 HOLE RED BAND COASTER ARM BEARING CONE WHICH HAD A BIT NARROW DIAMETER
IT IS ON THE UPPER COASTER
NOW I AM ABLE TO PRESS ON THE ORIGINAL 48T SPROCKET TO THE TANDAM COASTER
JUST NEED TO RUN A BOLT BETEEN THE 2 SO THEY WILL ROTATE CORRECTLY