This didn't seem to get much attention when I posted it in the MIT aero tips thread, so thought I'd post it again (since I'd gone to all the trouble of scanning in the images, etc. <g>):

http://home.earthlink.net/~acoggan/aeropositions/

Again, the wind tunnel measurements were:

Me on Hooker w/ 700C "front end":

@ 0 deg of yaw CdA = 0.238 m^2
@ 5 deg of yaw CdA = 0.233 m^2
@10 deg of yaw CdA = 0.232 m^2
@15 deg of yaw CdA = 0.224 m^2

Me on Hooker w/ 650C "front end":

@ 0 degrees of yaw CdA = 0.238 m^2
@ 5 degrees of yaw CdA = 0.227 m^2
@ 10 degrees of yaw CdA = 0.214 m^2
@ 15 degrees of yaw CdA = 0.213 m^2

Me on Hooker w/ Superman position (not pictured):

@ 0 degrees of yaw CdA = 0.214 m^2
@ 5 degrees of yaw CdA = 0.219 m^2
@ 10 degrees of yaw CdA = 0.222 m^2

Me on Wynn:

@ 0 degrees of yaw CdA = 0.274 m^2
@ 5 degrees of yaw CdA = 0.260 m^2
@ 10 degrees of yaw CdA = 0.263 m^2
@ 15 degrees of yaw CdA = 0.271 m^2

Now for some commentary:

1) note that while my CdA at 0 deg of yaw didn't change when I dropped my handlebars by ~4 cm (by switching from a 700C front wheel and fork to a 650C front wheel and fork), it was markedly lower at varying degrees of yaw. This effect was even more evident in a "head up" position more in keeping with what I tend to adopt under stress, e.g., in the action photo from master nationals in 1999 (data not shown). OTOH, when using the Superman position my CdA was markedly lower at 0 deg of yaw, but actually rose slightly with increasing yaw angle. I think this nicely illustrates the limitation of testing at only 0 deg of yaw (e.g., as one essentially must do when performing field tests using a powermeter), since we rarely, if ever, race under conditions where there is absolutely no crosswind (even on a track in still air, the yaw angle can approach 10 deg in the corners).

2) Yes, I realize that my saddle appears too high in the photo w/ the 700C "front end". I think this is because it was a staged (i.e., non-pedaling) shot, and that I was sitting further back on the saddle than I do when I'm actually racing. Indeed, you can see more of the back of the saddle in the two photos of the bike fitted with the 650C "front end", even though the action photo is taken from a frontal angle.

BTW, the reason that I took the staged photos in the first place is that I was trying to understand why I "sailed" so well in the 650C position (esp. w/ my head down), but not at all in the Superman position. I seem to have lost the frontal and 10 deg of yaw pics that I also took, but the overall impression they gave was that the lower, more compact position tended to help me cover up the bike better. This is consistent with the fact that, when tested sans rider* (i.e., me), my Hooker bike showed no tendency to "sail" by itself, either with the standard bars or with my jury-rigged Superman set-up (22 cm stem plus cut-off mini-MTB bars plus clip-on aero bars):

Hooker w/ Hooker bars:

@ 0 degrees of yaw CdA = 0.062 m^2
@ 5 degrees of yaw CdA = 0.066 m^2
@ 10 degrees of yaw CdA = 0.062 m^2

Hooker w/ Superman bars:

@ 0 degrees of yaw CdA = 0.064 m^2
@ 5 degrees of yaw CdA = 0.069 m^2
@ 10 degrees of yaw CdA = 0.066 m^2

*Somewhat regretably, these tests were conducted with the cranks vertical and with the Look-style Shimano pedals hanging in the wind. This makes comparison with Kyle's published data for the Hooker a bit difficult, since he tested with the cranks horizontal and w/o any pedals attached. Nonetheless, my data were w/in 10% of his.