18.29 (as shown)
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Felt AR build
The Ultegra Di2 build features a 53/46 mid-compact crank and 11-30T 11-speed cassette on a complete Ultegra drivetrain. As always, Shimano’s Ultegra Di2 shifting is superb, and the ergonomics of the hoods are comfortable. The mid-compact works well for the intended focus of “fast and flat”, and it handled the punchy, rolling hills of eastern Colorado quite well. With small bike frames, the spec’d crank arm length is always a crapshoot: is it gonna be 165mm or 170mm? I am comfortable enough on either and can compensate with seat height, but I appreciate that Felt paired the steeper chainring size with a 165mm crank arm. It does make it a bit easier to get my cadence up and accelerate more quickly or get my butt up a hill.
Felt made a slight compromise in their hunt for aerodynamic supremacy with regards to the stem and handlebar. While the leading edge of the AR is still optimized for aerodynamics, it isn’t at the expense of serviceability. The stem and bars are separate pieces, and by routing the cables under the stem, Felt made it possible to swap the stem without having to cut cables. This makes packing and travel quick and straightforward. You can also run a standard stem if you choose. Having the option to run a standard stem has no aero benefits, but certainly allows more flexibility in determining stem length as well as how many spacers you may need. And as a final point to show that Felt sweats the details, the faceplate of the stem is designed to integrate aftermarket computer mounts.
I’m a big fan of the “wider-is-better” trend in road cycling. While the AR only comes spec’d with 700x25s, the frame will accommodate up to a 30mm tire. The Continental Grand Prix tires roll well, but I would have liked to see a 28mm tire.
The one spec I struggle with is the wheel choice. I get it, the Reynolds AR 58s are a deep section wheel that’s tubeless compatible and features a 19mm internal rim width; they check a lot of boxes. They look hot and make sense on an aero bike, right? Sure. As long as there is no wind anywhere and you’re going in a completely straight line. The AR is an unapologetic aero bike, so this seems ok, right? Except Felt has touted all their research on yaw and they’ve emphasized how fast the AR is at yaw angles up to 10 degrees. It seems like a disservice to pair this frame with a wheelset that just can’t keep up.
Felt AR ride
The AR has an entirely new carbon layup designed to improve pedaling efficiency and increase vertical compliance, particularly in the back. Felt claims this years-long ground-up redesign has resulted in the following improvements over the previous AR:
- 11 percent improvement in lateral headtube stiffness
- 21 percent improvement in lateral stiffness of the fork
- 15 percent improvement in torsional stiffness of the fork
- 14 percent improvement in BB pedaling stiffness
I have been pleasantly surprised by how comfortable and well-balanced the AR is. Assuming a wheel swap, I can happily ride this bike all day. It’s noteworthy that the AR doesn’t have the severe seat stay drop that has become almost ubiquitous. That drop provides compliance, but it isn’t needed here. Felt has achieved that in other ways.
In addition to the carbon layup, Felt’s seatpost does a fair bit of work to reduce harsh feedback. The vertical split in the seatpost provides flex and compliance at the saddle. Felt also includes a plastic and rubber sleeve that sits just inside the seat tube. The sleeve is intended to reduce quite a bit of the “noise” that travels through the seat tube to the rider, thus creating a smoother-feeling ride, and based on my rides, it seems to be effective. The ride is smooth, without feeling dull or dead. I’m not suggesting that one method is inherently better than the other, but it’s nice that it doesn’t look exactly like every other bike.
Speaking of looks, it’s worth noting that the AR Advanced I tested showcases the paint for the yet-to-be-released AR FRD model (but is not an FRD frame). The actual paint colors for the AR Advanced are either a lovely aqua or white, both glossy. It’s also available as a frameset in a matte pewter.
The addition of thru-axles and disc brakes should be a given. The out-of-the-saddle stiffness and responsiveness of the frame is only enhanced by the thru-axles, and the Ultegra disc brakes have a nice feel and good modulation. I’m in agreement with Ben Delaney when it comes to thru-axle levers though. I know it’s an aero road bike and designing aero levers is probably not worth the effort, but (big sigh) I don’t want to dig out a tool just to take a wheel off.
Felt made a lot of changes when they introduced this latest iteration of the AR, but what they didn’t change was the fit. The 48cm frame has a snug 97.4cm wheelbase with 40.8cm chainstays, while the 71-degree head tube and 74.3-degree seat tube angles are relatively par for the course for small to tiny-sized performance-oriented road bikes. The stack and reach are 51.0cm and 36.7cm, respectively, which is on the more compact end of the spectrum. Taken all together, the bike fits and feels like the performance-oriented bike that it is. It isn’t severely aggressive, but it is certainly not a relaxed or upright geometry.
Aero by the numbers
We at VeloNews obviously aren’t testing bikes in wind tunnels on a regular basis, but the following lays out Felt’s claims regarding the aerodynamic improvements they’ve made in the AR.
Stated briefly, yaw angle is the angle between the rider and the direction of the wind. In order to optimize aerodynamics, yaw angle is taken into account. Felt cites substantial third-party research suggesting that cyclists spend the vast amount of their time at close to 0 degrees of yaw. In that vein, Felt provided these results of unweighted comparisons conducted by independent contractors at the San Diego Low Speed Wind Tunnel, and which compare the 2020 AR to the previous model:
Results — Unweighted Yaw Angle Ranges
- 0 degrees = 9.4 percent faster*
- -2.5 to 2.5 degrees = 7.0 percent faster
- -5.0 to 5.0 degrees = 5.2 percent faster
- -7.5 to 7.5 degrees = 3.2 percent faster
- -10 to 10 degrees = 0.7 percent faster*
“Faster” is defined as more aerodynamically efficient than the previous generation Felt AR.
In spite of the research suggesting that even +/-10 degrees may be conservative, Felt’s claim that the new AR is 1.4 percent more aerodynamically efficient in overall conditions than the previous iteration is based on an equally conservative industry standard of a 90/10 distribution to weight the time spent riding within that +/- 10 degree range.
Michael White, Felt’s senior marketing and communications manager, explains that Felt defines their use of the term “overall conditions” as a weighted calculation in which “90 percent of the cyclist’s time is spent riding between -10 and 10 degrees of yaw, and the remaining 10 percent of the time is spent riding between both -20 to -10 degrees and 10 to 20 degrees of yaw.” Keep in mind, this is also assuming you’re riding alone; if you’re in a paceline or group, you’ll spend even more than 90 percent of your time between -10 and 10-degrees.
More and more aero road bikes are simply everyday road bikes. While Felt proudly touts the bike’s aerodynamic features, the bike is comfortable and fun to ride. It’s far from the most lightweight bike on the market, and I’d love to see it shed a few grams (or a pound?). Having said that, it never felt sluggish or slow — again — it’s a fast, comfortable bike, so maybe the weight isn’t as big of an issue as it may at first appear.