The change in gear ratios really does help! We know that the amount of torque supplied to each half-shaft is equal and determined solely by the input torque on the middle differential gear due to the handle chain.
Unknown macro: {latex}
\large \begin
Unknown macro: {equation}
F = \frac
Unknown macro: {tau}
Unknown macro: {r}
\end
We decreased the radius for the wheel sprocket on the differential, which corresponds to a larger force, and this increased force is palpable when I rowed on our newly modified erg.
Our bungee cord set-up is supposed to look like this: 
That diagram is about as crude as our current set-up, swathed in steel cable and masking tape: 
By turning the wheel to stretch the bottom bungee cord as much as we could, we estimated, crudely, that the maximum displacement of the #41 chain is 12 inches. Therefore, the top bungee cord has about 12 inches of pretension in order to take up all possible slack in the chain