Tour de France tech: BMC’s latest road bike, the impec

BMC introduces its newest frame at the Tour de France. The impec boasts in-house carbon weaving and highly tunable ride characteristics.

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2010 Tour de France Tech: The BMC impec
2010 Tour de France Tech: The BMC impec

Not even 12 months after the world was introduced to BMC’s flagship road racing bike, the teammachine SLR01, the Swiss company is out with another new road bike. This time, they’ve chosen to reveal it under the lights of the grandest arena in competitive cycling: the Tour de France. It’s called the impec, and it marks a new progression for the Grenchen-based manufacturer.

“One hundred percent of this bike is made in Grenchen, in our factory,” said race team support liaison Stefano Cattai.

BMC joins forces with Stargate

“They actually weave the carbon tubes in Switzerland,” chimed in BMC chief mechanic Ian Sherburne. “Basically any other company in Europe gets tubes made. But they have what we call the ‘Stargate,’ this 12-foot, round weaver. There’s like 9,000 threads of carbon that come down right to the middle, and it comes out on a mandrel,” Sherburne described.

Time also weaves its own carbon fabric outside of Lyon, France, and so does Giant bicycles in Asia. But what’s unique to BMC (as far as we know) is that they’re weaving threads into carbon fabric and then molding the fabric directly into frame tubes.

Referring to the tube construction, Cattai said, “Here, it’s just with a machine. You can decide with a computer how many carbon fibers you need, the density, and you put in the numbers. You have one frame or 1,000 frames, all the same.”

In contrast to monocoque frames, which are typically made by hand-laying pre-preg carbon fiber into molds and inflating air bladders inside the frame to compress the material, Cattai says that BMC’s tube construction permits  precise control of fiber material, density, orientation, weave pattern, and resin density.

“The computer puts in the glue. You know how many grams of glue (resin) is inside, and where,” he said. “You have a number, you can control it.” Cattai added, “You can decide the shape, amount of glue, pressure, the density.”

The ability to control the tube construction translates into a new ability for BMC not only to produce this frame entirely in Grenchen, but also to achieve a high degree of tunability in the impec ride quality. Tubes can be built for stiffness or compliance in any orientation. Furthermore, each frame tube can be sized and tuned individually. Custom frame sizing and ride quality is therefore within BMC’s reach. The company’s goal with impec was to create a frame with just the right stiffness in just the right places, and just the right compliance to handle the rough roads of Europe.

2010 Tour de France Tech: The BMC impec
2010 Tour de France Tech: The BMC impec

Lugs? Shells? Lug-shells? How about SNC: Shell Node Concept

Along with the carbon tubes, the carbon frame lugs are made in Grenchen. But they’re not lugs in the traditional sense — they are actually more like two half-lugs that clamshell over the tubes at each  joint. The bond line between the two lug halves is clearly visible on the finished impec frames, and while it looks industrial, it’s in keeping with BMC’s well-developed aesthetic. They’re also made from carbon fiber.

Referring to the lugs or shell nodes, “We can’t change the angles, because that’s very expensive to mold,” said Cattai. “So we have standard angles. But we can choose the size of the tubes,” he said. Frame sizes and geometries for now will be standard, but the new-found flexibility in BMC’s manufacturing procedure for the impec might allow custom projects in the future.

Cattai said the new frame isn’t quite as light as the current teammachine SLR01, but he emphasized that BMC is currently more concerned with precisely tuning the bike’s ride quality than meeting an arbitrary weight target. And when the impecs are assembled, they’re still light enough to brush up against the UCI weight limit of 6.8 kilograms.

In terms of design elements, the impec bears most of the sport’s modern necessities. A BB30 bottom bracket, tapered steerer tube, internal cable routing, a proprietary seatpost shape, and integrated headset bearings are all part of the impec’s engineering.

Look for more on the new BMC impec in days to come.

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