Originally Posted by chaadster

Thank you…that was exactly my point to Seventwentynine earlier. Zipp's 808s also generate negative drag at higher yaw, providing, as I said earlier, actual propulsive force. As you rightly state, slower riders actually gain more aero advantage than faster riders because of the higher yaw due to slower speeds in the same wind conditions.

For terminological clarity (from CyclingPowerLab's site):

Given that most of us ride significantly faster than the meteorological wind is blowing, most of the time, the resistance wind tends to dominate. For example, if we ride at 40kph (24.85mph) with a 10kph (6.21mph) full-on sidewind (meteorological wind approaching at 90 degrees to our ride direction) the effective wind has a yaw angle of just 14 degrees. In fact modelling suggests that somewhere between 50 and 70 percent (let's say 2/3rds) of effective wind yaw angles experienced by a rider are lower than 10 degrees, the faster your ride, the higher this percentage. The same research suggests that a further 30 percent (let's say 1/3rd) of effective wind yaw angles are between 10 and 20 degrees. (http://www.cyclingpowerlab.com/Yaw.aspx)