The HSF Aeroflow isn't replacing the HSF Aeria. The aim for the Aeroflow is to work well with 31.8 bars - the hammerhead hides the 31.8 and the aerobar clamps. My goal is to make mortal bikes more super. As mentioned, production cost rises have blown out the original price targets, but still - a Tri Stem + Aeroflow is cheaper than an AU Stem + HSF Aeria.
As a more price oriented product the R&D that can go in is a bit limited. So what I did was measure the headtubes from the QR PR Series and Cervelo P-Series, then get my guys to make the shape of the bottle flow nicely. Those bikes chosen because they are the extremes of head tube depth on modern bikes and also are likely to be the most common models to have the bottle fitted.
Red looking at Cervelo, blue for QR.
The intent being to make the two parts look like one airfoil to the wind. Yes there is a gap as we don't have the rubber gusset of the HSF Aeria but in theory the flow should reattach
Then we did basic CFD to check what was happening at the bars
no bottle
with bottle
reduction in higher pressure areas by taking away faces that are presented to the wind
Won't know how well this has all worked until we get some testing done. But the principles behind the design are quite strong
From a functional viewpoint - being able to offer multiple sizes by simplifying (compared to HSF Aeria) the mould requirements then means that riders can choose the size that covers more of their head tube on larger frames. And for larger frames can carry a lot more fluid than previously possible. For small frames - the HSF Aeroflow 700 fits onto bikes that can't use the HSF Aeria.