When the new Felt AR was announced, serious questions about the performance of the bike relative to the increasingly crowded aero road bike category were raised. Felt promised to respond to these questions with a technical whitepaper. Well, Interbike is over and we have the data. We’d recommend you sit down and get comfortable for this one. Let’s get started.
Felt really did their due diligence in the tunnel for the new AR. They went to the San Diego Low-Speed Wind Tunnel – widely regarded as the gold standard for bike testing. The yaw sweep is not just the non-drive side of the bike, either. The AR and the six other bikes (technically seven, but we have to throw one out for reasons we’ll get into later) were run from -20 to +20 degrees yaw at 2.5 degree increments. To put that into perspective, each bike was measured seventeen times during their sweep for a total of 119 datapoints from Felt (136 if we include the second run of the AR with Felt’s test brake). Each bike’s components were identical and transferred between them for each bike’s run, as well as being setup for the same rider (i.e. stack, reach, distance to pedal, etc.). Also, the frames were all 56cm “or equivalent,” according to Felt. This is as close to an apples-to-apples test that we are likely to ever get.
Component list according to white paper:
|Wheelset||Zipp 404 Firecrest Clincher|
|Tires||Continental GP4000 (width not listed, photos show 23mm)|
|Component Group||Shimano Dura-Ace Di2 9000|
|Brakes||Shimano Dura-Ace 9000 F+R (Propel tested using proprietary, integrated brakes. AR tested using direct mount rear brake. New AR w/ Felt Brake using proprietary design)|
|Saddle||Selle Italia SLR|
|Stem||3T Integra (120mm, -10 deg rise shown in photos, Propel tested with standard stem due to 1 ¼ steer tube)|
|Handlebars||Zipp Vuka Sprint|
It is worth noting that Felt makes the following claim: “The choice of components was based on a typical, high-end aftermarket configuration and was entirely unbiased and not meant to influence the performance of any one bicycle frame. The specifics of the setups, such as the cable routing were optimized for improved aerodynamics and actual function.” The included photos from the whitepaper (gallery below) appear to bear out their claim of optimization and adherence to consistency of setup, which is admirable in this day and age of “tunnel data marketing.”
As noted above, in the interest of fairness of analysis, we will not be discussing the entry for “New AR w/ Felt F Brake” as it presents some fairly astounding drag numbers for an addition of equipment that we have no information on. Leaving that aside, let’s take a serious look at the drag graph above as it relates to the competition in general.
For those doubting Cervélo’s claim about the S5’s dominance of the aero road bike market, you have been both vindicated and disproved in the same tunnel test. Prior to the AR’s debut a month ago, the S5 was the clear frontrunner in the aero road bike category by a comfortable margin and is still arguably the best choice from -5 to 5 deg yaw. Impressive for a three-model-year-old bike, but the full sweep tells a different story, one that begins and ends with Felt’s new AR.
Out past +/- 5 degrees, Felt’s new wonder bike is literally unrivaled in the category, posting a drag curve that plunges to a 90g drag delta on the non-drive side—compared with the S5 at 12.5 deg—and maintains that lead through the rest of the sweep. On the drive side, the test AR maintains a lead of around 75g from -10 to -15 against the Cervélo, though the gap closes a touch out past -15 yaw. Against the S5, the newest bike from Felt Racing Division handily takes the win in the war on drag. Against the rest of the competition in the category, the data speaks for itself—the war was over before it even began—2014 sees a new king of the aero road bike in the Felt AR.
Felt’s new whitepaper also asserts claims as to “how much faster is bike X versus a Felt F1” and extrapolates them out to time saved versus the same bike, though we are somewhat short on details other than “…we used a weighted average with an emphasis placed on more common angles of attack such as 10, 12.5 and 15 degrees. The weights were derived from our experience of aerodynamic testing in the wind tunnel and real world.” We will leave them here, without comment, for the reader to make of what they will. For our part, we believe that the drag data speaks for itself: Felt has come out on top and been as transparent about it as is possible, which makes their victory all the more impressive.
We think the data is clear regarding the 2014 Felt AR and its trip to the tunnel with all of its friends—there’s a new sheriff in town and his name is Jim Felt. The competition has quite a bit of catching up to do. And according to this test, that is going to be no small task. Felt did everything right in testing their bike against the competition and came out ahead. From every angle, this is a test that shows what everyone has long suspected, and what the next generation has to compete with. Long live the Felt AR.
[Update: Felt Test Procedure – Felt 2014 AR v Comp Aero Test procedure Rev B-1 – AG]
[Update 2: The complete Felt AR 2014 White Paper – 2014_AR_White_Papers_8_26_13]