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Anemoi Aero Extension System - Optimisation & Testing
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Anemoi Aero Extension System - Optimisation & Testing

Creating our next generation Anemoi aero extensions has involved a vast amount of research, development, optimisation and testing to ensure that we are producing the fastest and safest extensions on the market. Here’s a look at just some of the development and testing we’ve done to bring you the best product possible.


Aerodynamics are what have driven our development of extensions since 2017. From extensive wind tunnel and track tests we know that the benefit is substantial, but we wanted to go further. So how can take our extensions to the next level?

We’re very lucky in that our supported team, HUUB Wattbike, are also partners with TotalSim, a world leader in computational fluid dynamics.  We took advantage of this to dig in deeper to the flow structures around the extensions and rider’s forearms. The section below is probably the most telling of the whole study. What you are looking at is a Z-plane section through one of the team rider’s forearms and our third generation extensions, showing the total pressure coefficient (CpT) and flow lines. This plot shows the separation and recirculation that occurs in the gap between the extensions and forearms, inducing drag. This has been a central focus of our development. We’ve taken steps to reduce that gap and create a smooth transition of the air flow from the extension to around the rider’s arm.


CpT oil flow Z-plane section plot

The most obvious feature to aid in closing this gap is the sunken arm rest. This was pioneered by us with the Pentaxia extension design, used by the HUUB Wattbike team in the 2019/20 UCI Track World Cup. It enables the extension upper face to begin at the same height as the top of the arm rest padding, giving one continuous surface from arm rest padding through to the extension tip. The second feature to assist in closing this gap is the concave top surface that allows the rider’s curved forearm to sit flush against the extension, providing a smoother flow transition from the extension.

The extension profile itself has been carefully contoured to fit a wide range of forearm profiles and handgrip angles. Utilising 3D scanning combined with rapid prototyping, we have been able to measure and confirm fitment and comfort across a wide range of athletes. We utilise the maximum width and height allowed under UCI regulations of 40mm x 40mm to create a leading-edge profile that efficiently displaces the flow around the arm whilst keeping flow attachment.

All of this means that we’re confident the Anemoi aero extensions will perform for a broad range of athletes from both an aerodynamic and ergonomic perspective.

Composite Layup & Testing

Using our experience in high performance composites applications and working alongside our UK based factory, we have developed the construction of the Anemoi aero extension system to provide the ultimate in combination of structural integrity, low weight, fatigue resistance and road vibration damping properties.  The mouldable nature of carbon fibre allows us to accurately form each pair of extensions to exacting tolerances, to ensure each extension is of the highest quality, time and time again. We use pre-preg carbon fibre, provided in CNC cut layups to our specification, meaning each layup is exactly repeatable, in terms of number of plies, ply weight and overall thickness.

Carbon Fibre Pattern
CNC cut carbon fibre pre-preg sheets

The carbon is then cured under high heat and pressure in highly polished aluminium tooling to provide the uniform, defect free finish seen on each pair of Anemoi extensions. The result is a pristine surface finish with no lacquer or treatments required - each extension is provided as moulded. We have coupled the benefits of carbon fibre, with aluminium 6082 T6 bonded hardpoints, so the major load paths are properly supported, providing the rider with reassurance that Anemoi extensions are not only fast, but safe too.

Out of the Mould
Pristine surface finish fresh out of the mould

The Anemoi aero extensions have been tested to ISO standard ISO 4210-5:2014, the safety standard for bicycle steering components. They passed. Exceeding the standard by 260%. A full safety test report will be released in the near future, documenting the full test process and results.

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