Those with a finger on the sportbike category’s pulse have had their gaze fixated on the Aprilia RS 660 ever since a concept of it was displayed at EICMA 2018. Rightfully so, as the RS 660 fills a vital role for the Italian manufacturer. It is its first fully faired middleweight offering, providing a street friendly but racetrack-capable alternative to the legendary RSV4 superbike. In a broader sense, the RS 660 also brings a level of sophistication and technology utterly unheard of in the class.
For decades, adding a 600cc inline-four cylinder or equivalently powered supersport model to its sportbike lineup has been the modus operandi of many a bike maker. The average 600 with their stratospheric redlines, peaky powerbands, taut chassis and racy riding positions are an absolute blast on the circuit — where they can be wrung out as intended.
On the street, few of those characteristics translate positively, unless you happen to reside at the base of an unpopulated mountain road. In traffic, the committed riding position weights the wrists something fierce, compounded only by the pain of stiff suspension and anemic engine feel, unless it’s spooled up to the heavens.
Instead, Aprilia carved out a niche within the still flourishing middleweight class, rubbing elbows with the likes of the iconic Suzuki SV650, Kawasaki Ninja 650, Yamaha MT-07 and Honda CBR650R, albeit with a raised pinky due to the $11,299 price tag. While all admirable motorcycles in their own right, their performance, power to weight ratios, equipment and electronics can’t match what the Aprilia RS 660 offers. This thing is entirely different, as I discovered on our first ride, beginning in Santa Barbara, California.
The RS 660’s story begins with its all-new 659cc parallel-twin engine, producing a claimed 100 horsepower at 10,500 rpm and a peak 49.4 lb-ft of torque at 8,500 rpm. Equipped with a 270-degree firing order that’s become fashionable in European parallel-twin engine design, the 660’s engine is a spunky little firecracker and belts out a downright mean exhaust note, reminiscent of the RSV4.
With smooth bottom end and roughly 80 percent of its max torque coming online at a low 4,000 rpm, the 660 has plenty of gumption right out of the gate, delivering loads of mid-range power. Oh, what a peach this engine is, pulling with authority up to roughly 9,500 rpm, where things start to trail off.
Best yet, all of that power is delivered in a tractable, exciting and approachable way — intermediate riders will appreciate the inviting, rousing performance, while experienced riders are going to relish every ounce of power. Whether you’re in the city or hitting your favorite twisty road, you will always have punchy acceleration at your beck and call, unlike typical inline-four supersports.
The RS 660 is tame at lower rpm, and the engine decidedly difficult to lug when trawling traffic. On the opposite end of the rpm spectrum, the single counterbalancer does well to hide vibrations below 6k, but above that, buzz is felt through the footpegs. I wouldn’t consider it a deal-breaker, though.
The sporty 6-speed gearbox offers precision shifts and is equipped with a slip-assist clutch that results in an impressively light clutch pull. Separating itself from the pack further, the RS 660 is the only middleweight bike fitted with an up/down quickshifter and it is a treat to use in the canyons, allowing you to blast through the gearbox with glee. The quickshifter works well most of the time, but occasionally, you will be met with longer kill times on the upshift and slight hesitation on the downshift.
From the beginning, the tagline for Aprilia’s new P-twin was that it’s the RSV4’s powerplant with the rear cylinder bank lopped off. While Aprilia engineers took inspiration from the 999cc and 1,077cc V4 engines, the 660 is its own entity. Evidence of its RSV4 lineage is best expressed in the intake design and varied length intake funnels, 48mm electronically operated throttle bodies, high 13.5:1 compression ratio and cylinder head design, all taking more than a few pages from the RSV4 playbook. It even shares the superbike’s 81mm stroke.
Helping you control everything is a Continental 6-axis IMU supported, class-leading APRC (Aprilia Performance Ride Control) rider aid package, lifted directly from the RSV4 and Tuono motorcycles. It includes 3-level cornering ABS, 3-level traction control, wheelie control, 3 throttle maps, cruise control and even engine braking management, which isn’t featured on the big bikes. In ABS level 3, the cornering function is enabled, while level 2 removes the cornering function for more aggressive riding, and in level 1, ABS is disabled in the rear only.
A total of five ride modes are standard: Commute (high intervention), Dynamic (sport riding) and Individual (customizable). Diving into the dash and switching from Road to Race will reveal the preset Challenge and custom Time Attack ride modes, that replaces your speedometer with a lap timer on the instrument panel.
All of those parameters can be quickly adjusted from the full-color TFT display found on several Piaggio models, but its easily navigable interface is updated for this application.
The street isn’t a place to test traction control or ABS limits, but I sure am glad to have those aids watching over my shoulder, especially when rolling through dusty apexes in the canyons. I stuck with Dynamic mode and enjoyed the crisp throttle connection, as well as the long leash for spirited riding.
What was crucial for the RS 660 platform is that the engine be as compact as possible to aid in a narrow and physically smaller chassis. A uniquely designed, lightweight aluminum twin-spar frame uses the 659cc engine as a stressed member to help save weight. Interestingly, each spar has one half of the head-tube cast into it and it’s completed when the two frame halves bolt together. Also, the cast aluminum swingarm connects directly to the engine, again saving weight.
With a leg thrown over the RS 660, it becomes apparent just how much emphasis was put on making the bike as sleek and svelte as can be. The footpeg distance is 0.72-inches narrower than the RSV4, and the subframe is 0.63-inches slimmer. Together, those dimensions make the relatively tall yet plush 32.3-inch seat height completely accessible for shorter riders. Additionally, the narrow subframe allows me to drive my weight through the footpegs, increasing control and feedback. For my 5-foot, 10-inch frame, the cockpit is spacious enough, although taller riders may disagree.
Faux riser clip-on handlebars integrated into the upper triple-clamp create a sporty yet sustainable riding position. Things can get wristy if you’re complacent on a longer ride, but it’s nowhere near as taxing as a supersport or superbike. Meanwhile, the 3.96-gallon fuel tank makes for a great anchoring point when braking or cornering. Aprilia representatives stated that they aimed for a riding position between the upright Kawasaki Ninja 650 and the racetrack-ready Yamaha YZF-R6.
Stylistically, the RS 660 references the RSV4 heavily and is equipped with LED lighting all around. Designers did add a bit of flair to the three-headlight RSV4 design by giving the RS 660 a daytime running light that extends upward on the front fairing in a “furrowed eyebrow” manner. The bike also features a functional passenger seat in standard trim, and when removed, luggage can be strapped to the bracket beneath.
A sportbike wouldn’t be a sportbike in 2020 without MotoGP-inspired aerodynamic winglets, and while the dual-layered plastics aren’t necessarily about creating down force, they are about encouraging rider comfort. The winglets are said to draw hot air away from the engine. In practice, it seems to work, as the engine’s radiant heat was rarely noticeable.
The supersport windscreen also provides a decent amount of wind protection when riding at freeway speeds, directing air toward the top of my helmet, and I can get into full-tuck comfortably.
A glance at the spec sheet reveals appropriately sporty numbers. Its short 53.9-inch wheelbase, steep 24.1-degree rake and 4.1-inches of trail pull no punches. However, this is where the Aprilia engineers have flexed their chassis knowledge against the competition — this bike is absolutely planted, translating tons of feel to the rider.
With a claimed wet weight of 403 pounds, the RS 660 tips into corners confidently and has a front end that encourages zealot-like faith. It’s light, nimble, and begs to be whipped into corners, remaining incredibly steady in every phase of the turn. Of course, Pirelli Diablo Rosso Corso II 120/70 and 180/55 rubber certainly contribute to the positive feelings. Thankfully, due to its reasonable power, the RS 660 won’t shred tires to the same degree its larger siblings will.
Handling suspension duties is a 41mm KYB fork featuring spring preload and rebound damping adjustment, accompanied by a non-linkage type KYB shock with the same adjustment abilities. The suspenders are tuned for street riding, soaking up bumps and bruises of the road nicely while still maintaining a composed and pleasurable ride. When the pace heats up, I would prefer a bit more compression damping, as sizable g-outs can unsettle things a bit. However, the all but officially confirmed up-spec Factory model will take care of that and appeal to those with a calendar full of track days.
In the front, radially mounted Brembo 4-piston calipers clamp onto 320mm floating rotors with good feel and stopping power — a noticeable improvement above the Japanese competition. In the rear, a dual-piston Brembo caliper grabs onto a 220mm disc and works well for line correction.
To call the 2021 Aprilia RS 660 anything but a game changer is an understatement, even with a couple minor teething issues. In a traditionally budget-minded class, reflected in paired-down components, technology and performance compromises, the RS 660 is trailblazing its own path. In essence, it’s the sportbike we always needed — real-world ergonomics, an energetic parallel-twin producing useable power, a stellar chassis and a swath of top-shelf electronics. Enough faffing around, let’s get it to the track.
2021 Aprilia RS 660 Specs:
Base Price: $11,299
Price as Tested: $11,499 (Acid Gold Color)
Horsepower: 100 horsepower @ 10,500 rpm (claimed)
Torque: 49.4 lb-ft @ 8,500 rpm (claimed)
Engine Type: Liquid-cooled, transverse parallel-twin, DOHC, 4 valves per cyl.
Bore x Stroke: 81.0 x 63.9 mm
Transmission: 6-speed, cable-actuated wet clutch
Final Drive: O-ring chain
Wheelbase: 53.9 in.
Rake/Trail: 24.1 degrees/4.1 in
Seat Height: 32.3 in.
Claimed Wet Weight: 403 lbs.
Fuel Capacity: 3.96 gals., last 1.05 gal. warning light on