As a reasonably new tandem team (8500km over a couple of years mainly road with some good length mixed terrain bike touring etc) I have been following this thread with interest . Cadence has been a talking point with my stoker initially she was unhappy at my higher (than her) cadence it took a while for each of us to adapt the end result being a compromise of sorts and she is now happier at the higher cadence end of things or though I prefer to spin and she likes to push harder at a lower rpm. I knew a crankset change would improve things but didn't want to spend money on shorter cranks as our tandem is at the entry level price point and we plan on upgrading. I had never heard of running the cranks just a little out of phase but with nothing to lose today I moved the captains cranks back 2 teeth. The change for both captain and stoker was monumental from the captains point of view its is like getting a run into the power side of the pedal stroke (a running start versus a standing start) and my stoker commented on how it felt like her every pedal stroke counted, judging by the panting that was coming from behind me she was working very hard. We ending up riding in a heavier gear than usual and laying into the pedals, we live on the side of a hill so all roads lead to a climb and I felt like we shared the effort more evenly which was also my stokers perception. Its a total game changer for us so you should give it a try before forking out for new cranks.,