How Cannondale Designed its Sleek New Road Bikes

How Cannondale Designed its Sleek New Road Bikes

From early experiments with big aluminum frames in the ’80s to more recent ventures in carbon fiber, Cannondale has worked to build a reputation as a bike innovator. That makes the company’s latest high-performance releases for 2019—the Topstone Carbon, CAAD13, and SuperSix EVO—both surprising and, well, not so surprising. Even a quick glance at these beasts proves that they represent a new evolution of Cannondale’s design philosophy. The general idea? Make bikes that are faster on the road and more capable off of it, thanks to some elegant technical tweaks.

 

There are plenty of features worth exploring on these new rides, but two key innovations stand out: The truncated airfoil design found on the CAAD13 and SuperSix EVO road bikes, and the Kingpin suspension on the Topstone Carbon gravel bike. Aesthetically, the tube shapes and dropped seatstays on these bikes are a departure from previous Cannondale frames. They’re design highlights you’d expect to see rolling out the door of an indie bike manufacturer. But these features aren’t just style gimmicks.

“The dropped seatstays and the airfoil tube cross-sections are really a result of the speed and comfort goals of these platforms,” industrial designer Ian Surra told Men’s Journal in an email.

The new CAAD13 and SuperSix EVO are the latest in Cannondale’s stable of race-oriented road bikes. Although built from different materials, they both share the new truncated airfoil tube design. When viewed from the front, the frame tubes are shaped like the leading edge of an airplane wing, but instead of flowing back to a tapered edge like a wing does, the back side is squared off—hence being “truncated.” Cannondale pioneered this shape on its SystemSix elite racing bike. But figuring out the right specs for the CAAD13 and SuperSix took three years of trial and error, Damon Rinard, engineering manager for Cannondale road bikes, said via email.

“A truncated airfoil, in the general sense as we’ve applied it, doesn’t describe a specific shape but an almost infinite array of shapes,” he explained. “The way these profiles are defined can have a drastic impact on performance.”

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The SuperSix EVO frame, showing the truncated airfoil design Courtesy of Cannondale

After experimenting with different airfoil-based tube shapes, Rinard and his team landed on the current version, which yields a hefty 30 percent reduction in aerodynamic drag. In wind tunnel tests, the SuperSix EVO created less drag than top-tier competitor bikes like the S-Works Tarmac, a $10,000 steed (the base model SuperSix, by comparison, retails for $2,200).

But does a sleeker frame actually translate to better on-road performance? Wind resistance increases with velocity, and I was curious to know if riders would only feel the benefit when they’re really cranking. In response, Rinard gave me a physics lesson that also doubles as sound life advice.

“Some important things aren’t noticeable; some noticeable things aren’t important,” he said. “Noticeable or not, aero drag is at work whenever the rider is moving, even when drafting and even at low speeds.”

He pointed out that at 30 miles per hour, the SuperSix EVO’s frame saves about 30 watts of power compared to the previous version of the bike. But even when pedaling on flat ground at around 9 miles per hour, aerodynamic drag makes up roughly half the resistance a rider must overcome.

“That difference in drag is still enough to make a performance difference even at relatively slow climbing speeds,” he said.

Aside from aerodynamics, the Cannondale design team has also obsessed over suspension, namely the new Kingpin system on the Topstone Carbon. It, too, is the result of years of experimentation—in this case, starting back in 2015.

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The Kingpin suspension system Courtesy of Cannondale

Suspension on a bike calls to mind shock absorbers, linkages, and the wonky mountain bike frames built to accommodate them. But the Topstone Carbon is a gravel bike; it doesn’t need all that. Instead, Cannondale attached the dropped seatstays to the seat tube with an axle that allows the stays to pivot. And they engineered the seat tube, seatstays, and rear portion of the top tube to flex under pressure. The result is a simple, lightweight suspension that amplifies the frame’s ability to absorb bumps (it delivers 30mm of travel at the saddle) without heavy, complicated shock absorbers. It’s the centerpiece of the bike, making it capable off-road and comfortable on the pavement.

“The Topstone Carbon was really developed around the Kingpin system,” said Surra.

The Kingpin has also been tuned to deliver the same feel for different frame sizes using a construction technique called Proportional Response. The positioning of the pivot connection on the seat tube, the cross-sections of the tubes, and the laminate design are all tweaked for each frame size. That means a shorter, lighter rider will get the same response as a heavier, taller rider. And because there are no shocks to pump up and the suspension won’t bottom out, the Topstone requires minimal maintenance and no adjustment.

“Ownership is more like a road bike than a full-suspension mountain bike,” said design engineer Darius Shekari in an email. “You just hop on and ride.”

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The new CAAD13 Courtesy of Cannondale

Together, the three new bikes show where Cannondale is headed. According to the designers I spoke to, both the Kingpin suspension and the truncated airfoil design will likely migrate to other models in the company’s lineup. The designs are a clear indicator of the company’s commitment to research and top-tier performance. More importantly, they lead to bikes that look great and can really haul, too.

”A phrase we throw around the studio a lot is ‘timeless design,’” said Surra. “We do away with a lot of the decorative detailing and focus on creating beautiful proportions and forms that are indicative of the function of the bike.”

 

 

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