Shimano Dura Ace - For the highest expectations. The Dura Ace is Shimano's lightest, most ergonomic and precise component group. It not only offers the finest mechanical performance, but also serves as a chassis for the revolutionary digital Di2 switching system. The additional 11th Gear allows a truly dominant performance in the form of precise, race-ready shifts. Polymer coated cable. The secret is a polymer coating that looks like hoses wrapped around the train under a microscope. This ensures a lower surface area that rubs against the inner case lining. Fat is also kept longer. The main advantages are a much lower effort when shifting and the feeling of faster shifting processes as well as more braking power with much less effort on the brake lever. OT-SP41 outer caseIn the OT-SP41, the outer shell is pre-lubricated along the entire length with a special silicone lubricant to allow fast, precise shifting. The OT-SP41 lowers friction losses of the inner cable to an absolute minimum so that the circuit responds quickly and is effortless to use. The driver is relieved by the elimination of shifting delays and high effort when shifting, especially in a terrain that requires frequent shifting or on the long distance.