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5/4/2009 | 2 MINUTE READ

Building a Better Carbon Fiber Mountain Bike

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Carbon fiber is as expensive as it is light.   So when Santa Cruz Bicycles, looked at building its first carbon fiber frame, the company wanted to avoid a bumpy ride.

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Carbon fiber is as expensive as it is light.  So when Santa Cruz Bicycles, (www.santacruzbicycles.com) an already a high-end, niche market mountain bike maker, decided to make its first carbon fiber frame for its Blur XC, price was, in fact, an object.  Says Joe Graney, Santa Cruz engineering director.  “For us, 90 grams of carbon material is a hundred bucks.”  That’s 3.15 ounces.  And realize that they’d never worked with the material before.  It would be like learning to cook with caviar or truffles.

Santa Cruz was late to the party, as most of its competitors have had carbon fiber frames on the market for years.  But most of those bikes include welded aluminum components, such as the dropouts, where the frame ends and connects with the rear wheel.  Santa Cruz was determined to build the entire frame in carbon, dropouts and all.  So Graney and other engineers purchased competitor bikes and “chopped them up,” but even those dissections did not fully reveal how different layers of carbon were arranged.

The company partnered with a manufacturer launching a new carbon fiber manufacturing plant in south China, one that only made components. It had never built a frame before.  Santa Cruz entered into an exclusive agreement to ensure no one else could copy the techniques, which remain a closely guarded secret.

“When you’re spending six figures in tooling before you see a damn thing, it’s really hard to make changes. So you’d better know your design works,” Graney says.  So to help ensure that ahead of time, the frame was simulated in PTC’s (www.ptc.com; Boston) Pro/Engineer Mechanica CAD software, which displays where the carbon plies need to be thinner or thicker given specific stress inputs, say a 250 lb. man descending a 50%-grade hill.  They also used PTC’s PLM On Demand software to streamline communication between the China production team and the California designers.  

Of course, each bike frame is ridden by all of the Santa Cruz 60-person staff as well as put through a 14-point test before it goes on the market.

Including its RockShox Monarch 3.3 shock, the Blur XC weighs in at 4.2 lbs., compared with its 5.7-lb. aluminum predecessor. From concept to its January 2009 production, the process took 16 months, not exactly a record for the company.

“We screwed a lot up this first time around, so we expect to be much faster in the next version,” he admits.

A lot faster, indeed: the second carbon bike  was released in April, 2009.  It took just 10 months to tool and build – a turnaround Graney calls “crazy, crazy fast.”--SEA


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