Feb 28, 2025
by Sam Park

Water Bottle Position Tests | Silverstone Sports Engineering Hub

Feb 28, 2025
by Sam Park

Clinton Butcher Age Grouper – Double Sub 7 style bottle Test

The results are disappointingly mixed rather than the obvious gain we were expecting.

After conversations with some professional athletes and other people who have visited Silverstone Wind Tunnel, the feedback is that setup tends to provide a much greater benefit if positioned closer to the rider – there is low air pressure directly behind the rider’s body, and filling this reduces CdA.

In addition, this lower air pressure is located higher, more behind the rider’s body rather than legs, so an upwards tilt will lead to a positive CDA change.

This is the only test we did for the rear sub7 style set up and did not do it with a single bottle or different angles, all the test protocols have paced.

As a result, we will be adapting our current mount to sit tight back on the seat and this will be on SALE at a very cost-effective price soon.
See below for images showing better bottle placement.

James Teagle Professional Triathlete – Double BTA Test

Donald Brooks Ironman Age Group World Champion – Rear Bottle Test – Tool Box – Down Tube Bottle

CDA Change at 45kph -10 to 10+ Green line indicates a lower CDA at points with the bottle and the red line indicates an overall a higher CDA without the bottle and its beneficial to use a bottle in this position.

CDA Change 45kph -10 to 10+ Green Line without bottle and toolbox, Orange with, this indicates that with this test subject that a down tube bottle and toll box is not faster.

The positive is that it is not much difference, so if you do need that area for hydration and tools it’s a no brainer.

Donald has informed me after speaking to a high-end Professional athlete that she tested faster with the toolbox and down tube bottle.

James Teagle - BTA Bottle Test

Bottle in Bottle out -5 to 5+ YAW at 40kph and 50kph it’s a clear advantage to run a bottle between the arms to close the gap about 4 watts at 40kph and 6 watts at 50kph.

In James position this is a clear indicator of how many watts you save running a single bottle in a very aero positions, if you are less aero and have a bigger gap between your arms and body the watt savings may well increase.

Check out https://www.absolute-speed.com/ they do a great system.

James Teagle / Ben Redman – Down Tube Bottle Test

We did not test the down tube bottle in the tunnel, James had informed us that https://www.orbea.com/gb-en/ TT bike tested faster with the down tube bottle after his velodrome testing in Portugal, this bike is actually made to be faster with the down tube bottle on, the reason behind this would be due to the deflection from the bottle onto his calf’s.

The Idea of this test was to add a bottle holder that deflected the air onto the calf’s and create a smother air flow when an athlete is riding the bike, this was based on evidence we had from James Teagle and Velodrome testing with the large Precision Hydration bottle, so it lead us to believe that on a wider frame this concept could work, but in this case on the Boardman thin frame it was an absolute fail, so I would avoid anything on the down tube apart from an aero bottle, even this has showed to be a very slight loss.

Please check out our EZ Gains “cost effective gains” science page if you are interested in going faster

The Science