The biggest differences between these tests and the earlier ones JC did were, from my reading:
-rider on bike
-fatter tubes on bike
This being the case, the results were different than when he tested for the bike alone, that being a skinny steel frame. How? From what I read...
The water bottle on the frame DT is actually a boon with a larger diameter frame member. The larger tube (relative to a skinny steel tube,) in front of the bottle, makes for a smoother transition, and the wind sees this as an increase in surface area/depth of the DT. The tube is effectively deeper, and may also be cowling the seat tube, minimizing the negative effect of the big hole in the middle of a diamond configuration frame.
With a rider on the bike, a lot changes, and the placement of a profile-style bottle on the front may well provide some sort of a fairing benefit. Perhaps it is helping with the dirty air in the knee/lower torso area? I would like to see what effect the bar/bottle height has on this number.
The rear mount bottle #'s are really interesting, and are counter to what JC has been saying for a while. These numbers are saying that higher is better. Very curious.
I have a sneaking suspicion that the riders back profile could have a profound effect on this #.
I would love to see these #'s with a larger sample size. This is VERY interesting stuff, but the rider on the bike is adding a pretty substantial variable to the testing, and I would liike to see how much these #'s change in a more varied sample/with other riders...
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