Shimano’s dominant position within the bike industry is based totally foremost on one simple fact: They may be able to forge metals with a creativity and sophistication some distance beyond anything their competitors can dream. Shimano factories are crammed with VW Bug-sized forging machines that spend all day long pounding alloys into highly precise little bits that — after final assembly — make a Dura-Ace bike brake and shift and look so fine. Shimano = Forging. It is so simple as that, and that is the reason the the reason is, they long resisted the temptation to wander into the arena of carbon. The remainder of the industry, in fact, embraced carbon with an untrammeled cheek-to-cheek, two-arms-and-two-legs enthusiasm, and whilst they were at it, they accused Shimano of being a fuddy-duudy for no longer doing the similar. Shimano’s position was once simple: Anything carbon can do, forged metal can do better — lightness, durability, cost, you name it.Still, there is something cosmetically sexy about carbon. And market trends are what they’re — consumers vote with their wallets, and they’re opting for carbon. With the Dura-Ace 7900 series components, Shimano proves that whilst they are going to move deliberately, they’re so much surely no longer fuddy-duddies. Living proof, the Dura-Ace RD-7900 rear derailleur –The Dura-Ace RD-7900 is Shimano’s first ever rear derailleur that makes use of carbon fiber. The pulley cage and P-body are both made from carbon to shave off 16g compared to the RD-7800 rear derailleur. Shimano states that their selection of carbon vs. alloy here has no detrimental effect to long-term durability of the derailleur. And whilst the carbon vs. alloy debate has a timelessness to it akin to Red Sox vs. Yankees, there is something else occurring with the RD-7900 that — no less than to us — is some distance bigger news: It has an expanded chain wrap capacity compared to the RD-7800. What’s chain wrap capacity? It is a simple arithmetic equation: (Big ring – Small ring) + (Big cog – Small cog) = Chain Wrap Capacity.