When SRAM first introduced its groundbreaking 10-speed Red component group, the heart of the industry-shaking design was 1:1 Exact Actuation technology. In ordinary terms, this means that with each shift the derailleur pulls the same exact length of cable, regardless of what gear you're in. 1:1 is simple to set up, it stays in adjustment longer, and it provides laser-accurate shifting. This advancement sent competitors scrambling to one-up SRAM -- cranking it to 11 or going electric. SRAM's engineers didn't buy the hype, and instead of 'me too-ing,' they've put massive efforts into improving their 10-speed drivetrain. The result is that the Red Aero Glide Rear Derailleur benefits more directly from the lessons learned over the life of first generation 1:1 than if SRAM were to start from scratch.
The Red Aero Glide Rear Derailleur now has a clean, air-cheating, low-profile mounting bolt that's made of titanium to keep weight as low as possible. The long upper knuckle clears 28-tooth cogs, and it is made of extremely stiff forged aluminum to resist flex, which helps to maintain perfect gear alignment. The inner carbon fiber pulley plate has also been enhanced to resist flex, increasing rigidity for precise gear changes, and its low weight results in a light action.
SRAM continues to run their Black Box ceramic cartridge bearings in the pulleys. Ceramic bearings offer outrageous hardness and roundness in comparison to steel, which reduces mechanical drag by a substantial amount. After aerodynamic drag, mechanical drag is the leading source of power loss.
The pulleys themselves were a focus area for SRAM engineers, and they improved weight, durability, and operation. Coined AeroGlide, SRAM optimized the jockey wheel's profile so that the chain will glide more efficiently over the tooth profile as it threads through the cage. This helped silence a notably noisy drivetrain and enhanced chain movement across the cassette. Most would call it a day with those advancements and skip out early for a ride, but SRAM's R&D team developed an elastomer coating to further quell pulley noise.
The SRAM Red Aero Glide Rear Derailleur also receives a barrel adjuster for simple fine tuning, and because it continues to use Exact Actuation technology, it's compatible with all SRAM shift levers: Red, Force, Rival, and Apex.