By Matt Pacocha
On the eve of the 15th edition of Germany’s Eurobike trade show, Scott USA took over the famed Graf Zeppelin Haus in downtown Friedrichshafen to unveil two new models for the upcoming 2007 season, both focused on setting new lightweight and engineering standards in a very competitive marketplace.
The Addict road frame, soon to be Saunier Duval’s new ProTour race machine, tips the scale at just 790 grams (56cm), while the original prototype Spark full-suspension mountain frame, now used by Thomas Frischknecht on the World Cup circuit, weighs in at 1700 grams (with rear shock). Scott claims that production versions of the frame will still weigh in at slightly less than 1800 grams (medium).
Addicted to carbon
The only metal parts found on the new Addict road frame are the replaceable derailleur hanger and the press-in races for the headset bearings, like those on the CR1. Everything else, including the bottom-bracket shell, cable stops and front derailleur hanger, is molded from carbon. The all-carbon frame also features a new carbon manufacturing process called “Internal Molding Process” (IMP). A departure from the carbon miter and wrap of the CR1, it is also patented, something Scott USA’s chief engineer Peter Denk said should have been done with the CR1’s process. The IMP process presumably uses some type of removable inner mold or mandrel, and does not use the traditional monocoque molding method. The results produce a continuously molded carbon piece that does not suffer from the imperfections of traditional monocoque molding. The inner surface of the frame is as clean as the outside, allowing less material to be used to achieve the same marks for stiffness and durability. The rear triangle is molded to the front triangle using the traditional miter and wrap method.
The frame features an integrated seat mast, and due to dealer requests it also has a removable alloy hanger that bolts to the carbon fiber main dropouts. There will also be a non-integrated version available. The matching fork also sports carbon-fiber dropouts. It has a target weight of 320 grams, down from the CR1’s fork weight of 395, although the initial production forks weights are claimed to be closer to 300 grams.
The final carbon component is the bottom-bracket shell, which is made solely from carbon and unthreaded. Scott contacted Shimano to manufacture Dura-Ace bottom-bracket cups specifically for this bike; they are unthreaded and can be press-fit. Shimano obliged, making it possible for Scott to go forth with the carbon bottom-bracket design.
“[The Addict is] 100 percent carbon fiber bottom to top,” said Denk. “The frame at this moment is 790 grams, yet it meets the test standards of the CR1.”
As it did with the Addict, Scott went all out shaving every gram from the Spark, producing this new weight-obsessed cross-country racer from scratch. At the core of this bike, too, is the new IMP process. Using this new method of molding, and drawing from the experience of longtime Scott-sponsored athlete Thomas Frischknecht, Scott believes it has created a world-championship contender.
Scott liked how the pull shock worked on its Genius bikes, but decided that when combined with its three-position traction-control feature the 500-gram shock was just too heavy to achieve the weight it wanted for the Spark. So Scott went to shock manufacturer DT Swiss and offered up its traction-control technology in exchange for DT’s lightweight damper internals. This formed a partnership Denk described as “combining the best of both worlds.” The Scott-branded, DT-manufactured unit tips the scales at 240 grams.
“For Frischy it’s only weight, stiffness and traction control,” said Denk, who said he could have made the package even lighter had he left the traction-control feature out. “But he [Frischy] said, ‘no, no, no we need traction control.’”
The Spark features an integrated seat post – like its road counterpart – and carbon-fiber cable stops. As with the Addict, there will also be non-integrated versions available. Alloy is used for the bottom-bracket shell, linkages and rear disc brake mount. For these applications, especially the brake mount, where heat build-up is an issue, alloy is still a better medium. The linkage pivots on sealed cartridge bearings. The bearings are packed with a proprietary water-resistant grease, with hopes of extending their life in adverse conditions.
The frame is made of what Denk described as “very forgiving” intermediate modulus carbon fiber, which he says is very resistant to damage from impacts and has a high “crash resistance.”
Finally Denk described the Spark’s geometry as perfectly balanced between the forgiving slack angles of the Ransom and the razor-sharp precision of the Scale hardtail. The angles are slacker than those on the Scale, something he thought Frischknecht wouldn’t approve of, but when the Swiss star asked Scott to have one ready for the world’s just two weeks before the opening ceremonies, Denk knew he had a winner.