Thanks for all the insight. I understand that variables can make a comparison difficult, although seeing a pretty constant 20-25% difference on the same route ridden many times seems to point to something material. It was also sticking in my mind that when comparing all the technology differences from a great 2002 tandem to a great 2013 tandem, I'd perhaps stay even, vs seeing that level of drop-off. Anyway, it's not a huge deal, but I did want to understand if there was a design/technology rational for this, (not to mention give my wife a good answer when she asked "why are we going slower on this expensive new bike you had to buy?") Thanks again all!