Originally Posted by
Carbonfiberboy
Since she's a fit runner, she'll probably prefer a cadence of somewhere around 100 for a field test, maybe higher. My guess is that she's slim legged and that you're under-utilizing her talent. Try giving her a higher cadence normally, see if she likes that better. I ride with a couple of tandems who pedal ~100 normally. So experiment with cadence on a ride, see what works better for her, then try the field test.
In any case, she shouldn't be frustrated. I'm sure she's doing it right!
I was wondering about the OP trying a different cadence, either higher or lower than he might normally select, to see how it affects the ride.
To some extent, one can adjust perception of cadence with crank length.
So, a longer crank length will be perceived as a higher cadence, and a shorter crank length will be perceived as a slower cadence.
Anyway, first try a difference cadence/gearing choice, taking one out of one's comfort zone, and see how it impacts the ride. Then perhaps consider adjusting crank length for either the stoker or captain, or both.