AeroGeek’s Hydration Guide – BTA

In this post we will be covering the BTA (between the arms) bottle setup.  The BTA position is universally considered one of the best—if not THE best—place for a triathlete to keep nutrition (if you do not believe me then check out Cervelo’s P5 with the integrated BTA mount).


The benefits of this location are from the aerodynamic benefit of hiding the bottle in the aero dynamic shadow of your arms combined by the convenience of having a bottle always accessible for fueling on the fly.  The negative? Well, there really isn’t one.  Below we will cover a number of variations on the BTA theme.  All have the benefits of BTA, but we feel that some of the solutions are superior to others.

The Cage Only


This is the simplest solution where a single bottle cage is mounted between the aerobars.  This can be done simply with zip tie, Velcro, or with a more complex solution such as Profile Design’s HC Mount (here) or XLab’s Torpedo Mount (here).  The benefit is the simplicity. Just mount it up and you’re ready to go.  Any bottle grabbed at an aid station is easily stored and accessible at will.  The negative is that you have to move your arms and leave aero to take a drink.

The Vertical Solution


When one thinks of BTA, the first item that comes to mind is the Profile Design Aerodrink (here).  This is what I call the vertical BTA solution.  The liquid is stored in some kind of vertical bottle.  There are a number of different variations on this such as the previously mentioned Aerodrink and Torhan’s Aero30/Aero20 solutions.  The benefit is that with the straw, nutrition is conveniently at your lips with no need to break aero.  All of the solutions offer some sort of refilling port which allows easy refilling from either a bottle kept onboard or nutrition grabbed from an aid station.  The negatives of the vertical solution are that they hang down below the bars and interrupt the air hitting the head tube (which your bicycle manufacturer has spent a great deal of money to craft).  In addition, to date, all of the vertical solutions have shipped with straws that require you to move your head to the straw instead of moving the straw to your head.  While this seems like a minor issue, the convenience (and safety) of a soft straw is greatly appreciated once you try it.

Here at Aerogeeks we have sampled two solutions from Profile Design.  First is the standard AeroDrink. And second is the slightly larger but much “cooler” Aerodrink Insulated (here).  The versions are extremely similar, each carrying 22 oz of liquids.  The largest difference is that the plastic of the Insulated version is thicker resulting in a weight penalty of 39 grams and an aero penalty as well (though we don’t have a definitive answer of how much).  The fact that the insulation actually works nullifies those negatives however.  During our rides with the insulated version, liquids stayed chilly for lengths of time similar to those found with a Camelback Podium Chill.  When it comes to a choice between these two designs, we would go with the insulated version on all but your coldest of rides.


We have not yet had a chance to sample the Torhans solution, but for a vertical solution, this may end up being the best (here).  The advantage of the Torhan’s solution is that they actually designed and tested their solution in the A2 wind tunnel in an effort to find the most optimum design available.  From the shape of the bottle to the fairing built around the straw, it is easy to see what Torhans has done in the creation of this bottle.


Below is a summation of the data they found.  Obviously since we were not there to validate the data or methods, we can’t fully accept this at face value (especially since we find it hard to believe the XLab mount would be less aero than the Torhans). However, we do appreciate what Torhans is trying to do by creating a truly aerodynamic solution that meets the needs of the triathlete.

TorHans Data

The Horizontal Solution


The horizontal BTA solution is new to the triathlon world with Speedfil’s A2, which was the first to popularize this concept.  With the horizontal solution, you are getting both the refill port and straw of the vertical solution combined without the aerodynamic drag penalty.  By going with a BTA solution you can use a similar mounting option as the cage only solution.  On my bike I just strap the bottle to the bars using Velcro.

The A2’s refilling port is unique in that unlike the ports on PD’s bottles, the port is sealable by the rider and has virtually 0 splashing.  In fact, the seal is so tight that you may want to leave it slightly open to make it easier to get liquid through the straw.  An added benefit of the A2 is that the straw itself is a soft straw that you can pull towards your mouth. Therefore it does not require you to reach your head down to pull a drink from.  An added benefit of the A2 is an awesome support staff.  Initially I had a small manufacturing flaw in my bottle.  They immediately shipped me a new bottle with no question and then helped provide information on the best mounting options using their experience setting up Andy Potts.

Aero HC Bottle

With the success of the A2, it is not surprising that we are starting to see competitors in the horizontal BTA setup.  The first looking to come to market is Profile Design’s Aero HC System.  First shown at Interbike, it has many of the same benefits of the A2 (horizontal design, refilling port).  An additional benefit is the integrated computer mount at the rear of the cage.  We’re extremely curious about this system.  It looks to be much more aerodynamic than the A2 with the curved bottle nose and hidden computer mount. In fact, we have come to nickname it the “submarine” for its profile, including the coning tower like refill port.  One concern we have with this bottle is that it has gone back to the hard, inflexible straw of the Aerobottle.  When we’re able to test this bottle, we imagine we may swap the straw to a more flexible option.

At Aerogeeks we consider the horizontal BTA solution to be the optimum solution for all multisport activities.  Combining the aerodynamic benefits with the easy access of the location, it’s really an easy decision to go with a BTA setup.  All three of us use a BTA solution—with both Devon and I using the A2.  I personally have swapped out the standard bottle the A2 comes with for a Hydrapak Wooly Mammoth bottle (here) to get some insulation for my drinks.  We heavily recommend any rider looking for a better hydration solution to take a look at this type of solution—specifically the A2.

8 responses to “AeroGeek’s Hydration Guide – BTA

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    • The original Wooly Mammoth works with no issues. However there was a redesign last year and we havent tried the new ones yet.

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