Where is it most aerodynamic to put your rear bottle holder? I was curious about this and asked my sponsors at StacZero if they could help me answer this using the virtual wind tunnel. After having scanned my position at Sykkeltilpasning in Drøbak outside Oslo they had a virtual figure of me on my QuintanaRoo in the aero position. With that, we could play around. This is what we found out:
While all there numbers seem fairly similar we should have a closer look at how this could be more than marginal differences.
We decrease our aerodynamic performance from baseline with another aero bottle on the downtube by 36 seconds, which we carry with us in all the other setups. Looking closer at position C and D we find a substantial difference.
Where you should put your water bottle, of course, depends on several factors. How many bottles do you need? And do you have a strong enough bottle holder to keep them in place at position D? For that case the Xlab Gorilla XT is my recommendation.
My general advice would be:
- Only use an aero bottle on the frame, and preferably on the seat tube
- Have a bottle in a rear bottle holder as much as position D (not C as I first mistakenly wrote) as possible, even if you are not planning to actually use it
- Having a regular bottle between the arms is the best solution in terms of practical use and aerodynamics.
And last, train on your setup and makes sure it can handle bumpy roads.