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The Invention Process at Pivot Cycles

12.19.2014 | Online Media

http://www.mountainflyermagazine.com/view.php/pivotal-moves.html

The Invention Process at Pivot Cycles

words by Jen See | imges by Devon Balet

Walk through the back door at Pivot Cycles and enter a wonderland of inventive bike design and machine shop magic. Housed in an archipelago of industrial buildings, Pivot designs its bikes from schematic drawings to hand-built prototypes in Tempe, Ariz. A new model may go through five generations of prototyping before owner Chris Cocalis declares it ready for production.

“Where other companies will do a set of drawings or a 3D model and send it over to the factory, we follow the process through completely,” Cocalis said. “We start with the design, [make] the tooling for the design, and prototype the parts. And then we’ll build a lot of fixtures for production and ship it to our partners.”

Cocalis welded his first steel frameset in 1988, and over the course of his career in the bike industry, he says he has experienced every step in the production process. “I still have the first frame I brazed,” he said. “It’s funny, because I’m not a super sentimental guy. It was sitting up in my garage, and the original dirt from 1988 was still all over it.” The bike was painted bright pink in the style of the era.

To ensure quality and precision, Pivot designers build and deliver their custom frame fixtures—including this custom rear triangle fixture designed by Bill Kibler—to the manufacturing facilities in Taiwan. (left) Bill Kibler and Sean Kennedy set up a prototype frame in the welding table (right).

Two years after building that first bike, Cocalis started Titus with the goal of producing custom bikes on a short turnaround time. During the 17 years Cocalis owned at Titus, the company built just about everything in house. He estimates he drew approximately 5,000 custom frame designs. He and his Titus team also developed a quiver of production techniques to speed the process of cutting, assembling and welding framesets.

When Cocalis left Titus in 2006, he was already thinking ahead to his next project, and he launched Pivot the following year. Though Pivot currently works with factories in Asia to produce its bikes, Cocalis takes a hands-on approach to production that is similar to how he worked at Titus. He is not the sole designer at Pivot, but the bike designs carry his thumbprint.

New Pivots begin as a set of geometry numbers based on Cocalis’ experience building custom bikes. Cocalis designs the geometry and sizing to reflect the purpose of the bike. Is it a long-travel downhill rig? Or is he building a lightweight cross country ride? He also sets the desired suspension travel benchmarks during this first stage of the process.

 

Bill Kibler flushes debris in the CNC machine from what is to be a bottom bracket assembly.

After he determines the basic geometry, Cocalis sends it to Dave Weagle, the mastermind of the DW Link suspension platform. The two designers work together on the pivot placement and suspension details. “I work back and forth with him, and we balance what I want with his miracle calculations,” Cocalis said. “And then things hit, like tires hit seat tubes, and you have to throw the calculations out.” It can take a few iterations to bring Weagle’s suspension and Cocalis’ overall design concept into line.

Cocalis tells a story to illustrate how the process works in practice. He was working with Weagle and Pivot’s mechanical engineer Kevin Tisue on a new bike, and they had set up the parameters of how they wanted the bike to perform. Weagle crunched the numbers, and they went back and forth without making much progress. Finally, Weagle called Cocalis, excited that he’d come up with the perfect anti-squat curve for Pivot’s design parameters. “I’ve got it! This is going to work perfectly,” Cocalis recounted Weagle saying. “There’s only one problem: There’s no place for a front derailleur.”

In that particular case, the pivot points Weagle envisioned took up the space typically occupied by a front derailleur. At the same time, Cocalis was working with Shimano on the pressfit 92 bottom bracket and also envisioned mounting an e-type front derailleur directly to the frame so as not to take up real estate on the seat tube. “Some of my previous design ideas had met with similar complexities,” he said. Pivot developed the pressfit 92 bottom bracket design in conjunction with Shimano, and Pivot had one of the first asymmetric bike designs to mount the front derailleur directly to the frame.

Sean Kennedy welds a bottom bracket assembly.

Initially, Cocalis planned to design his own suspension system for his Pivot frames, but suspension design is a minefield of competing and sometimes overlapping patents. “I found myself crossing into Weagle’s backyard,” he said. DW Link sets the dual pivot positions to control the compression of the suspension from rider weight. “Weagle is the keeper of those ‘anti-squat‘ calculations,” Cocalis said. Weagle’s math problems and Cocalis’ geometry numbers create the foundation of each bike’s design.

Then it’s a matter of turning the geometries and suspension design into actual bikes. Tisue works out the specifics of the bike’s moving parts, while the company’s two industrial designers hone the shapes. Cocalis encourages his designers to be as innovative as possible, but he remains closely involved in each step of the process and continues to drive the general look of the bikes.

Sometimes, that means teaching the CAD programs new tricks in order to create more flowing lines. “There’s a lot of bikes out there that, to me, just look like they follow the steps that the computer wants to draw,” he said. “Oftentimes, we have to find ways to break the cycle of how the computer program works or trick the program into doing more complex shapes and curves.” Cocalis wants Pivot bikes to look as distinctive as possible.

A machined prototype bottom bracket assembly before it is welded together (left) and after it is welded together (right)

Tisue provides the drawings for the prototypes, and machining expert Bill Kibler translates the drawings into real life bikes. Kibler and Cocalis have worked together since the Titus days. Kibler had previously owned a machine shop where he did contract work for IndyCar teams, the aerospace industry, and companies like Titus. He has worked with steel, aluminum and titanium. When Cocalis decided to start Pivot, Kibler sold his shop and joined the Pivot team full time. Now he masterminds the prototyping and production process at Pivot.

A typical design cycle at Pivot can include five or six rounds. “We start with more basic prototypes just to vet out pivot points and make sure the way it’s been designed on the computer is the way it actually feels,” Cocalis said. Bottom bracket height, head angle and chainstay length are all variables that Cocalis may alter during the early stages of the prototyping process.

From the Pivot headquarters, it’s a short ride to nearby trails that offer the perfect proving ground for mountain bike suspension. The terrain in Phoenix is rock-filled and unforgiving. The climbs rise up steeply from the desert floor, and run-off from the winter rains carves deep, bike-eating ravines into the hillsides. Trails dip in and out of dry creek beds littered with tennis-ball-sized rocks. Cocalis and his crew spend many hours testing their creations in this desert playground.

As the prototyping process advances, the bikes begin to look closer to a final product, and Cocalis focuses on details, such as cable routing and tire clearances. Though the prototypes are alloy, the goal is to make them resemble the final carbon designs as closely as possible. “The carbon bike is always going to look more organic and swoopy and everything,” Cocalis said.

But the design does have to be perfect because the molds for a single size of a carbon bike can cost $75,000 to $100,000. “Everything is as perfect as you think you’re going to get it. That’s when you’re pulling the trigger when you’re doing carbon design,” Cocalis said. “That’s an end game.” Pivot’s carbon bikes are produced in a low-volume factory that works with other composite brands, such as Enve and Cervelo. “It’s the elite of the elite,” Cocalis said.

When Cocalis first launched Pivot in 2007, he did not include any carbon bikes in the lineup. Though he had worked on a carbon full-suspension design at Titus, Cocalis felt that carbon technology was not good enough yet to put into production. In testing at the time, he found aluminum still performed better in terms of durability and stiffness. It was five years before Pivot introduced its first carbon bike, the Mach 5.7, in 2012.

A Pivot machinist cope mills the joint of a seat tube and a top tube for a prototype frame.

When it comes to bike design, Cocalis is a perfectionist, and the development of Pivot’s Mach 5.7 carbon frameset required close to three years. The complexities of working with carbon in part accounted for the length of the process. “We’re at a level where the carbon bike has to be stronger than the aluminum bike,” he said. “It’s the most asked question: How’s the carbon going to hold up?”

The stresses on a full-suspension carbon bike come from multiple directions and require innovative tube shapes and diameters. To make the frameset strong enough, the front triangle of a carbon full suspension bike may weigh more than an entire lightweight hardtail design. “You’re going to beat the shit out of it in a different way,” Cocalis explained. The carbon lay-up will often use lower modulus material, which is heavier, because of its ability to take the abuse that a 5-inch travel bike typically receives.

Pivot’s work doesn’t stop with the bike design. Cocalis also builds tooling and fixtures to ensure that the bikes are built correctly in the factory. “We talk about the order that things need to be welded and how the tubes need to be cut,” Cocalis said. The production process requires both technical and cultural negotiations, and Cocalis is constantly pushing his manufacturing partners to try new things. “They always say ‘no’ first, ‘that’s impossible.’ But once they’ve seen it done, then they can do it.”

Understanding how the factories are organized and which workers are paid the most has helped Cocalis improve the quality of the finished bikes. Typically, welders receive the highest pay and are paid by piece. They want to weld as many frames as possible. “They don’t want to put it in a fixture and take it out of the fixture,” Cocalis said. “They just want to get it done.” Sometimes that means frames are welded quickly and imperfections are fixed later in the process.

Designing his own fixtures and sending them to the factory is one way for Cocalis to assure his bikes’ quality. “A bike frame always wants to go back to the way it was welded,” he said. Though an aluminum frame can be straightened or twisted after it’s heat-treated, Cocalis wants the welds to be perfect from the start. But he also needs to make it possible for the welders to work quickly, so they make their money. With that in mind, he devotes significant time to engineering the production process for each Pivot model.

Checking the fit of the coping in a dropout before the welding.

In the Tempe shop, Pivot has the same welding table used in Asian factories where many of the world’s bicycles are made. “In its normal state, it’s kind of crap,” Cocalis said. The table is not easy to calibrate, which means that quality can vary across production runs. “They’ll have this big piece of paper that’s a 2D blueprint, even though you have a very swoopy 3D arc,” he said. “They’ll set this up where they think it looks good. You could be 2 degrees off on the head angle. That’s the difference between a road bike and a mountain bike!”

For full-suspension bikes, even small errors in the welding process have significant consequences for the finished bike. The placement of the pivot points is especially crucial. “The tolerances on good dual-link bikes are like 0.1 mm, and the bike doesn’t ride the same,” he said. To solve this, Cocalis and his team create fixtures that fit on the welding table and hold the tubes precisely in place. The goal of all this effort is to ensure that the bikes are welded perfectly every time.

As a designer, Cocalis prizes practicality and function. At Titus, Cocalis kept to a stripped-down aesthetic. The bikes were often nude metal or carbon with simple decals. “In my mind, if you painted anything, it was like, why. Once you got to the point of ride perfection, that’s fine,” he said. At Pivot, he has put a higher priority on style and color, and his two industrial designers ensure the design is as well thought-out as the bikes’ geometries.

All the same, Cocalis remains an inventor at heart. “That’s the part I like best,” he said. “You go from nothing to something new. And it’s yours. No one else has it. For me, that’s what it’s all about.”

On December 12 Pivot Cycles released their latest creation, the Mach 429 SL, which is a lighter and more refined version of their popular 29-inch trail bike. Read more about the Mach 429 Here.

To learn more about Pivot Cycles please visit www.pivotcycles.com


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