Lots of feedback. Great discussion. Thanks!

More about the bike setup. . . . I should say I intentionally left out some details because I thought it would be more interesting to get gut reactions in a more theoretical bent rather than, "oh well, obviously. . ." I mean, we all "know" that certain things make riding "easier", but how much easier? How much is marketing hype and how much is reality. At what price points do things become noticeable and when do they cease becoming noticeable?

Regardless, the wheelsets are actually moderately different and I should really swap them, just to be sure. If the weather holds this weekend, I will report back.

I already messed around with the fit, didn't make any noticable difference, except tightening the tension on the pedals made by adducteurs happy. . .

Anyway, yeah, 2 mph is "a lot", hence my query. We ride the same route Wednesdays (I've done it at least 17 times). I had been riding the '86. switched to the '96 (for some reason, I forget) and then back to the '86. . I track with GPS. The '86 I get between 15.8 and 16.5 avg, the '96 I get between 17.2 and 19.1 avg (I took the CAAD 10 out once and did it in 20.4 avg, but part of that is exuberance, I imagine) This is all rolling terrain.