SRAM X0 DH - First Look

Jun 28, 2011 at 12:56

What is it: SRAM's X0 drivetrain has been designed to be versatile enough to span the gamut of uses, and true to form, we've seen it mounted on everything from top flight cross-country hardtails to World Cup downhill bikes, all with great success. But SRAM's high end product range is driven by their competition focused BlackBox racing program, a development team consisting of some of the world's top riders who, with the help of SRAM's engineers, are always developing components that are designed to get them over the finish line faster. Consisting of a new rear derailleur, chain guide and a carbon-armed 83mm crankset, SRAM's new X0 DH family is a specialized component range that was born from the BlackBox program and is designed for the very focused world of downhill racing, 4-cross and slalom.




How is X0 DH different? The 10 speed X0 DH rear derailleur looks very similar to the standard X0 unit from a distance, and the difference is not easy to spot, save the "DH" moniker on the carbon cage, even when both units are in your hands. But the difference is in the P knuckle - the segment between the cage and parallelogram - which is shorter on the X0 DH derailleur than on the standard version. This seemingly small modification has a drastic effect on how the derailleur functions, allowing the upper pulley wheel to track the tight ratio DH cassettes that racers use closer, which results in more chain wrap, faster shifting and a more reliable setup under demanding conditions. A standard X0 rear derailleur has enough clearance to easily handle today's modern wide range cassettes that feature 36 tooth large cogs, but you'll never find such a wide gearing range on a downhill race bike - they'll usually feature a 26 or 28 tooth cog at the largest position - and while a standard derailleur can and does shift quite well when combined with a tight ratio cassette, getting that upper pulley wheel even closer to the cogs should improve reliability and shift speed, two points that racers are always looking to improve. SRAM's head of drivetrain development, Chris Hilton, expands on the role that the BlackBox program plays in product development:





Carbon DH cranks: While the new rear derailleur is certainly noteworthy, the carbon X0 DH cranks are actually the first DH specific carbon arms that use an 83mm bottom bracket spindle on the market and weigh in at an impressive 750 grams - including the bottom bracket and 36 tooth ring. How different are the X0 DH cranks from the standard X0 arms? The carbon arms themselves, besides now being offered in a 165mm version, are actually the very same as used on the conventional model, but are mated to a longer and burlier 83mm spindle (a DH strength 73mm spindle is also available) to allow them to be fitted to the majority of downhill bikes on the market. Again, the BlackBox program played a major role in the X0 DH crankset becoming a reality, with Sam Hill using his BlackBox modified X0 cranks, which were actually a modified standard X0 crankset shortened to 167.5mm, to take gold at the Mont Saint Anne World Championships.







Pinkbike's take: Downhill racing is arguably the most specialized discipline of our sport and often requires the most specialized equipment as well, with aggressive riders putting demands on their gear that the components would otherwise not see. Pinkbike has to give major props to SRAM for developing a component family, however small the niche, that downhillers have been requesting for years: more reliable shifting that should perform better in race situations, and components that can survive on a DH race bike that are still relatively lightweight.

Visit the SRAM website to see their entire lineup.

Photos by Sven Martin