FELT AR ULTEGRA DI2
£6299 Stiffer, more aerodynamic and with an angle-adjustable seatpost
Felt’s original AR – ‘Aero Road’ – was released in 2008. The silhouette of the 2020 bike looks similar but, as always, the devil is in the detail. Tube shapes and carbon layups have been refined, exposed cables have disappeared while carbon wheels and hydraulic disc brakes feature.
The latest, 2021, AR retains a slim frontal profile but is more muscular in shape, with wider, kammtail aerofoil tubes providing more stiffness. Felt says the improvements in this area are in the double digits, in percentage terms, but what matters is that the new AR feels taut, responsive and exciting. The position on my 56cm bike is typically racy, with stack and reach figures of 561mm and 394mm, respectively.
The seatpost is split for comfort and has a saddle clamp you can flip to change the seatpost angle from 73.5 degrees to a more time trialfriendly 78.5 degrees. The 100mm stem combines with the 73.5-degree head-tube angle for a front end that responds quickly to steering inputs.
The rider causes around 80 per cent of the drag, so it’s crucial to adjust fit parameters to achieve an aerodynamic body position. It’s an area where aero bikes often trip up, sacrificing adjustability for integrated components that save a few watts in the wind tunnel but don’t take a rider into account. The AR avoids this, save for one minor point.
The Sprint carbon stem is Felt’s own and uses a standard handlebar mount, so you’re not tied into using the Devox Aero bar. It’s a great handlebar but it’s nice to have the choice. The stem and bar have also been designed for travel. The cables are routed through the stem’s underside, allowing the handlebar to be removed for packing without disconnecting any cables.
The downside is that the handlebar height can only be lowered if you cut the steerer tube. The stem is also only available in a six-degree angle and can’t be flipped for extra height, though this shouldn’t be an issue if you get a bike fit. The cables can also be routed semi-externally so you can use a standard stem but this would require overhauling the cabling.
In terms of aerodynamic performance for the bike alone, Felt claims a 9.4 per cent improvement over its predecessor, the 2014 Felt AR at 0 degrees yaw (ie a straight headwind). That’s said to be worth around 10W at 48kph. That’s compared with a bike that was already pretty slippery, and you can tangibly feel the difference all of the aero optimisation makes to your speed. It’s great fun if you like going fast.
Deep frame tubes and wheels, and disc brakes, do add weight and at 8.28kg my bike was 210g heavier than the Vitus and around a kilo heavier than an all-rounder. A kilo might look significant but outside of long, steep climbs it’s a difference that doesn’t affect performance much; aero bikes really are faster in most situations.
This AR gets a Shimano Ultegra R8070 Di2 groupset, with 52/36 chainrings and an 11-30tooth cassette. Shifting is unflappable and I appreciate the 30-tooth sprocket. The Ultegra hydraulic disc brakes, meanwhile, provide plenty of stopping power in all conditions and though noisy when wet, they still slow you down well.
The Reynolds AR58 DB wheelset and Continental GP5000 clincher tyres are also excellent, and contribute a lot to the Felt’s speed. They’re very easy to handle on windy days, which is impressive for wheels with 58mm-deep rims.
The 19mm internal rim width boosts the 25mm tyres to around 26.5mm at 65 PSI. It makes for a ride that’s on the firmer side, especially on rough roads, but it’s very fast on good roads. There is room for tyres up to 30mm wide, although anything over 28mm will compromise the wheels’ aero quality.
Overall, the Felt AR is an accomplished aero road bike, with few compromises and a practically flawless spec. It’s carrying a little extra weight, but it’s hard to argue with its superb performance.
An accomplished aero road bike, with few compromises and a practically flawless spec