New AR is Felt's "most aero road bike ever"

Felt says that the updated AR is not only its most aerodynamically efficient road bike ever, it also offers an improved ride quality, better handling, disc brakes, clearance for up to 30mm tyres, and "a level of real-world functionality and integration that is ideally suited for all riders".

"It's not just faster, it's better in every way," says Felt – which isn't an unusual claim, let's be honest. 

Here's the new AR in a nutshell:

• Disc brake-only
• Clearance for 30mm-wide tyres
• New seatpost module that's over 100% more compliant than previous AR
• New semi-integrated front end
• 9% faster than the previous generation AR 

Aerodynamics

Felt worked with data that says cyclists spend the majority of their time riding in conditions of relatively low yaw (-10° to 10°), and used computational fluid dynamics (CFD) software to create hundreds of virtual permutations of new airfoil shapes, taking many physical models to the wind tunnel for validation.

Of course, they also had to evaluate the structural characteristics of each airfoil design. There's no point having an ultra-aero design if it's not stiff enough. Get details on stiffness claims below.

One aero development is what Felt calls the 'fish lips' on the seat tube. This flared section helps blend the aerodynamic profiles of the seat tube and the tyre/wheel.

"It allows for more tyre clearance without creating a significant gap between the tyre and the seat tube, which would otherwise increase aerodynamic drag," says Felt. 

"A frame without 'fish lips' on the seat tube can only be optimised for one tyre width [but] the AR can accept multiple tyre sizes, up to 30mm, while still having an efficient blended airfoil between the frame and the tyre/wheel assembly."

Felt gives these figures comparing the new AR with the previous generation (based on measurements made at the San Diego Low Speed Wind Tunnel):

• 0° yaw          9.4% faster
• -2.5°–2.5     7% faster
• -5°–5°          5.2% faster
• -7.5°–7.5°   3.2% faster
• -10°–10°     0.7% faster

Felt doesn't say what wind speed those figures refer to, and it doesn't offer comparisons with bikes from other brands.

"We'll say with confidence that the new AR is 1.4% faster than the previous AR in overall conditions," says Felt, basing that figure on a weighted calculation that takes into account the distribution of time a road rider spends at specific ranges of yaw.

Stiffness

Felt claims these figures comparing the stiffness of the new AR with the previous version:

• 11% improvement in lateral stiffness of head tube
• 21% improvement in lateral stiffness of fork
• 15% improvement in torsional stiffness of fork
• 14% improvement in BB pedalling stiffness

Seatpost

Felt says that the profile of the AR's seatpost has been fine-tuned for aerodynamics but the split design remains from the previous version. 

Why the split? Felt gives these reasons (in Felt's own words):

• It allows for an aerodynamically optimised interface between the post and the frame's seat tube junction.
• It allows the two halves of the post to flex and shear independently of one another, which increases overall rider comfort.
• It allows for the use of a proprietary clamping mechanism that is designed specifically around the unique properties of carbon-fibre.

Felt has now created a rubber damping sleeve that lives within the junction of the seatpost and the seat tube, the idea being to add compliance. 

Felt claims that the new seatpost provides 112% more flex than that of the previous generation AR, and that the potential to tune ride quality is in development.

Disc brakes

Felt says that it was sold on the benefits of disc brakes at the start of the design process for the new AR but that it had to work hard to incorporate them while also reducing drag.

"It all came down to a new airfoil paradigm, and a painstaking development process of optimising how those airfoils interact across the whole of the bicycle," says Felt.

Also, the dropouts are countersunk so the custom thru-axles sit flush with the frame and fork.

Real-world usability

Felt says that it has spent a lot of time ensuring that the new AR is easy to live with.

"Because most of us do not ply our trade racing on a professional cycling team and have an army of world-class mechanics to do the dirty work of bike maintenance, we committed ourselves to making the new AR the best possible bike for all riders, so we knew from the outset that the AR would have a traditional front end, with a separate handlebar and stem configuration, and without a fully integrated cable routing system," says Felt.

The cables are routed under and through the new oversized stem to hide them from the wind without making mechanical work more difficult.

The stem can be removed without affecting the cables and can be swapped in minutes.

A stem faceplate has been designed for use with aftermarket computer mounts.

Availability

The all-new Felt AR aero road bike is available now in six frame sizes and two component packages, as well as a frame kit option.

We don't yet have UK prices but the prices in Euros are:

• Shimano Ultegra Di2 build €6,399
• Shimano Ultegra mechanical build €4,999

https://eu-en.feltbicycles.com/