Stoker and I train on singles or spin bikes about the same amount as we ride our tandem in the winter. I notice that it's possible for the tandem to "corrupt" my pedal stroke. We have a timing belt, which makes it a little more sensitive, but I definitely notice when we are pedaling circles and when not. Stoker does, too. So there's an incentive to fill in the circle to round out the weak points. Theoretically, one of us could hammer the downstroke and the other only do the bottom and backstroke and we'd have a nice team stroke. I do notice that does happen to me when I do roller work on my single after only riding the tandem for a while - specifically my backstroke gets weak, so I expect Stoker is filling in for me.

So I have a question for those who go to the trouble of using a trainer with their tandem: why? Do you think it's better to keep working on that team stroke and ignore one's single performance? Or does one team member get a much better workout on the tandem? Or do you just enjoy training, not only in the same room, but on the same bike?