I find ridding with aero bars on the tandem (Santana) to be more stable than on my single. If shifting is needed then I take my right hand off the aero bars, shift, and move it back to the aero bars (in 1 or 2 seconds). If the climb is >2% and longer than a few hundred feet then I ride on the drops. We use the sweet 16's front and back. Wer use to average close to 25 MPH on a flat 10 miles course.