Polygon's Square One will be the first bicycle to feature the Naild's R3act rear suspension system, and the reason you need to know about this truly new design is that it rides like no other dual-suspension mountain bike you may have experienced. Big statement? Perhaps, but I have had the opportunity to trace the development of R3act 2 play, the first production version of the design, for three years running, and during that time, I watched some of the sport's heavy hitters scratch their heads in awe after riding the prototypes. More recently, I was given production-ready machines for final evaluation - an experience that made me wish I had not worn the words "groundbreaking" and "revolutionary" into cliches, because I have a proper use for them now. The Square One EX9 we introduce here has 180 millimeters of ultra plush rear suspension, but unless you were told, you wouldn't know that fact until you dropped into a rowdy descent. More about that later.
Where Did R3act Suspension Come From?
Today, we classify trail bikes by the amount of suspension travel that they possess. The reason is simple: as dual-suspension designs gradually progressed from 100 to 170 millimeters, riders either happily or grudgingly accepted a number of compromises between pedaling efficiency and suspension performance. Even with the addition of technological band-aids like anti-squat kinematics, pedal platform switches, remote travel adjustments, lockout levers, inertial controls and reactive electronics, experience has taught us that, at various waypoints, we trade pedaling efficiency for a more technically capable (and heavier) chassis, and we have names for those benchmarks of compromise: cross country, trail, all-mountain, and enduro.
R3act suspension derives its enviable anti-squat attributes largely from its telescoping "monostay" swingarm. The stanchion tube is visible inside the pocket ahead of the bottom bracket.
Designer Darrell Voss thinks otherwise. "I don't believe that suspension travel should necessarily be part of that equation," says Voss. "Let's face it. Most riders are out there to have fun, and they can only afford one bike. If it pedals efficiently, what is the downside to having more travel?" Voss spent the past nine years working on a suspension system that erases nearly every downside of long-travel rear suspension. Heard that before? Yeah, probably from me, among others. Voss, who is a ripper downhiller, wanted an 180-millimeter-travel trail bike that pedaled as well as the best 120 bikes, but with a suspension that could track the ground like his DH machine. It took him a while, but he figured out a way to do it. It's called "R3act" - a tribute to Newton's third law - and it looks like it was derived from part of an alien space vehicle.
- Dennis Yuroshek photo
Let's face it. Most riders are out there to have fun, and they can only afford one bike. If it pedals efficiently, what is the downside to having more travel?—Darrell Voss
I'll forgive you for not knowing Voss. He's about as enigmatic as a six-foot, seven-inch-tall genius who has a zillion bicycle related patents can be. Soft spoken, he prefers to work behind the curtain, beginning his engineering and design career with Klein Bicycles in the late 80's, which led to a series of design partnerships and manufacturing operations
in Asia that ranged from bicycle construction, to suspension products, key components, and even a magnesium forging facility. Voss's wide range of experience and tenure in the mountain bike world affords him a broader view of the sport. He lives on the vanguard of technology, but he becomes much more animated when the conversation shifts from extolling the virtues of the latest ten-thousand-dollar superbike, to how it may be possible to squeeze all that performance onto one that only costs only five thousand - which is why he founded Naild, and why Naild's first major project was R3act suspension.
R3act is designed to be a complete rear suspension system that Naild plans to sell to bike makers, along with any assistance necessary, to help them integrate it into their own frame designs. Presently, two bike brands have signed on. Polygon, and another well-known brand that will be debuting its version shortly. The basic suspension configuration is adapted to incorporate variations in suspension travel, wheel diameter and frame sizing. The design of the frame's front section, its geometry, components, and the bike's intended use are left to the customer.
Internal hoses, tucked from harm's way and full-width chainstays.
The rear axle plays an important role in the stiffness of the swingarm.
Why Elevated Chainstays?
Naild's carbon monostay swingarm is simply the most efficient way to provide an ultra-rigid structure that can incorporate the suspension's tubular sliding element. Shut your eyes and think "bicycle" and you will probably imagine a classic double diamond frame, garnished perhaps, with bits that relate to your style of riding. That's what a bike frame is supposed to look like, right? And, if you were making a frame from steel or bamboo, the double diamond design would be the best possible, time-proven way to build it. The addition of long-travel suspension, however, and the availability of engineered materials, like heavily manipulated aluminum or carbon composites, encourage designers like Voss to deviate from accepted fashion in order to solve new engineering challenges in more effective ways.
OK, here's the nerdy part: Voss admits that the basic concept is not new, and sources two bike designs that used sliding elements to help isolate the suspension from pedaling-induced chain tension: Paul Turner's Maverick and the evolution of Yeti's sliding carriage and present sliding column suspension. His version, however, takes the concept further. The heart and soul of his R3act suspension is a large stanchion tube that pivots near the bottom bracket that the monostay swingarm slides on. The stanchion tube is angled precisely to direct chain tension to counter suspension bobbing, and also to provide an "anti-squat" vector that, unlike the present dual-link suspension designs, remains very consistent through the bike's gear range and suspension travel.
Voss' ace in the hole is that the sliding member apparently balances opposing pedaling and suspension forces so well that a small impact can activate the system. That, and the fact that shock damping is reduced to the absolute minimum, allows the R3act system to track rough or uneven the ground with uncanny accuracy.
What that mumbo means to normal people is, you can pedal the bike in or out of the saddle and as hard or as softly as you want, and it will keep the tire hooked up without having to care about or compensate for what the rear suspension is doing. And, it accomplishes that without the need to engage platform levers, use electronics, or employ damping filters.
Anti-squat at zero sag.
Anti-squat at full compression.
Change in anti-squat vectors with each cassette shift.
No Fuss Suspension
Voss would be angry if I continued to baptize readers with suspension kinematics and techno-sermons about R3act. He's spent a measure of his life attempting to debunk the hocus pocus that marketing and media hacks have heaped upon a mechanism that he believes should be a simple to operate. "Sure, R3act's kinematics are complicated to describe," says Voss. "But, the rider should never have to think of that. Set the Square One's sag at 25-percent, get the low-speed rebound close and go ride. There is nothing else to do."
Truth is, that's all there is to it. No rubber bands in the air can, no knobs to fiddle with. In fact, Voss had to work closely with Fox to provide an X2 shock with almost no rebound and compression damping to optimize its performance. After testing, Polygon deemed the shock's platform lever unnecessary and eliminated it entirely. Voss calls it "Ground Tracking" suspension, because the way that R3act uncouples braking and pedaling forces allows the wheel to follow terrain so closely that most riders initially think something has gone wrong back there.
Polygon Team rider Mick Hannah said, "At first, I thought the rear brake wasn't grabbing. If I wanted to slide around, there's just so much more grip available, I had to use more lever to break traction. I found I could brake much later because of it." Indeed, the Polygon stays composed under braking, and it can level just about anything a proper DH bike can - better in situations like braking bumps - and it somehow manages to perform those tasks regardless of speed. Go figure.
If I wanted to slide around, there's just so much more grip available, I had to use more lever to break traction. I found I could brake much later because of it.—Mick Hannah
- Dennis Yuroshek photo
Presently, R3act swingarms are made from carbon, which is probably the best use of that material. To boost stiffness, the monostay structure is intentionally boxy where space or clearance is not a concern, so the large, hollow part lends itself well to carbon composite manufacturing techniques. The shock is driven by an aluminum yoke that pivots on plain bushings. Lateral forces on the swingarm are controlled by an aluminum rocker link near the mid-line of the swingarm that controls braking inputs and counters lateral forces. The sliding element is a large-diameter hard-anodized aluminum tube which pivots on ball bearings inside a pocket, forward of the bottom bracket. There is no spring or damping assembly between the swingarm and the stanchion tube, it is simply a sliding interface that telescopes as the suspension cycles.
The unusual bottom bracket placement is necessary to position the swingarm's sliding element where it can help generate the ideal anti-squat action. In spite of the offset seat tube and bottom bracket structure, the chassis is quite rigid. At full compression, the swingarm nests into the offset.
Both the rear derailleur housing and brake hose are routed internally through the Boost-width swingarm, and its 12-millimeter quick-engagement through-axle is Voss' own design. Protecting the swingarm's moving bits from weather and mud is an integrated plastic fender, which came in handy during winter testing. Protection is also provided in the form of a thick screw-on plastic bash guard that is intended to ward off rock strikes where the chassis protrudes forward of the bottom bracket housing. The guard was missing from our Polygon test bike, which resulted in an ugly, but only cosmetic impact crater on the corner of the frame. A second, unnamed test bike had the guard installed and suffered similar impacts without damage.
Square One EX Geometry
The Square One EX's offset seat tube and unusual bottom bracket support structure give the impression that the chassis has a very slack seat tube angle, but that is not exactly the case. Measured in a straight line through the saddle to the bottom bracket axle, the Polygon's effective seat tube angle is 73.5 degrees with the stock, set-back KS LEV dropper post, and one degree steeper with a conventional zero-offset post in place. Polygon's reluctance to join the steeper is better seat tube movement is its only nod to conservative all-day trail riders. From there, the Square One's chassis reflects contemporary enduro numbers with a generous reach, a sufficiently low bottom bracket good stand-over clearance and a 66-degree head tube angle.
The Polygon's rear suspension does not settle noticeably when climbing steeply, which compensates for its 73.5-degree seat tube angle and keeps the legs feeling fresh. - Dennis Yuroshek photo
The size large weighs 13.94 kg (30.67 pounds) A bit heavy for a carbon trail bike, but considering that it has 180mm of wheel travel, it must be strong enough to be ridden as a single-crown DH bike.
What motivated Polygon to partner with Naild and adopt the R3act Suspension System?
We decided to expand our market internationally, and we wanted to look for something new and innovative. In our mind, we wanted to keep our company progressive. We saw Naild bring in a technology, totally outside of the box - genuinely - which solved the very basic problems that keep happening in the development of suspension technology for bicycles. In the end, Polygon and Naild have the same simple goal which is, to make people happy when they ride
- Dennis Yuroshek photo
Why did Polygon decide to drop the shock's pedal platform lever?
We found how well the bike suspension system works with all the damping controls being completely open, and with all of the testing we did, there was no single occasion where our test riders thought they needed to switch off or tweak any setup on the shock, on the fly.
Can the Naild system be adapted for aluminum construction?
It has the potential to go that direction. Seeing how this system works - there is so much potential that we can explore, and to bring it to a more affordable level, surely is one of them. How soon? ...Let's say we have several projects with Naild ahead of us.
It has been a while since I've seen an innovation as relevant to the moment as Naild's R3act suspension system, and the fact that Polygon is the first to launch it, underscores the possibility that Darrell Voss's invention may fall directly into the hands of riders who need it most. The present enduro/all-mountain bike has evolved to the point of near perfection, but at a cost. Its pedaling efficiency, climbing ability, and edgy performance is dependent upon sophisticated suspension, the lightest construction methods and the best drivetrain parts. Here is a suspension system that can deliver better pedaling, superior suspension action, and greater versatility - and it requires no special components - at least for the rear suspension.
At a moment when the sport is choking on carbon caviar, Voss and Polygon offer a simpler alternative: How about we skip the science class and ride one bike that can do just about anything we'll ever need a mountain bike for? The Square One EX 9 is not perfect, but it's darn close, and it's a first try. R3act suspension, and the bicycles that are built around it, are only going to improve, which is bound to light a fire under the butts of some of Polygon's very conspicuous competitors. Just when we thought that trail bikes couldn't get much better, Voss and company leave the industry with no other option.—RC