How to hold aerobar extensions

We tested 4 common positions used when holding aerobar extensions: 

HANDS WRAPPED

This position is quite common for newer riders. It involves holding the underside of the ends of the extensions with your palms facing upwards and your wrists twisted inwards. This position is used by newer riders who may be more cautious with handling on aerobars, but increases tension especially at the wrists.

VERTICAL HANDS 

This is a position where your fists are facing in the direction of the airflow, common if you have  extensions that turn upwards at the very end. 

DROPPED HANDS  

This position drops the hand slightly, and is used if  you have aerobar extensions that are not flat/horizontal.

HANDS ON TOP 

This position is sometimes seen where riders rest one hand on top of the other one, either for occasional comfort over long distances or to achieve a higher hand position for UCI races where extension height is constrained.

In order to test aerodynamic drag we went to an outdoor velodrome, and our test rider Malachi performed a series of repeats of each position using a power meter, whilst we also measured environmental variables such as wind and air density.

Malachi was wearing a Nopinz skinsuit and an aero helmet (KASK Mistral), aero gloves and socks, and he was riding a Specialized Shiv bicycle with AEOX Titan and Disc wheels.

The data was  processed as in our commercial outdoor aero sessions, using custom scripts to establish a CdA (aerodynamic drag) for each position.

CdA is the combination of both frontal area (the A part of the equation) and drag coefficient (Cd), and is reported in m².

The CdAs and power output differences for each of the positions tested can be seen below.

As we've found on many riders that we've tested over the past 10 years (>1400 test sessions completed), the dropped hands position where your hands are slightly tilted downwards, and you keep your thumbs inline and touching together, is very often optimal and exactly what we found in this test. This is why we have designed our Angles extensions and Ascalon extensions to enable you to easily and comfortably hold this hand position when you ride.

The reason why this hand position is more aerodynamic is because, unless you have a near vertical arm position, the airflow travelling over the tops of your hands is more likely to stay attached and flow down your upper forearm, rather than detaching and causing a low pressure wake around the wrist area (which increases aero drag).

Holding your fists forward in the vertical hands position is more likely to cause this detaching airflow.

The wrapped hands position increases frontal area and doesn't allow for smooth airflow transition down the upper and outer arm.

The final position, the hands on top position is often more personalised than the others - on some riders this can be as quick, sometimes quicker than dropped hands, but in this example it was a little slower. This position in particular is very important to test to see whether it's quicker for you.

In this test we found that, similar to many other aero tests, the dropped hand position provided the best aerodynamic drag and for our test rider Malachi was his natural and comfortable hand position when using Angles extensions.

Although stack height, extension reach, arm inclination angle and arm rest width is all personal, the way you hold your hands on the ends of the extension is another factor to consider when you're looking to optimise your position for a time trial or triathlon.