Quieter, lighter cassette
To mount up the old Powerdome cassette, the OG1090, was to announce every shift and pedal stroke to the world. It was obscenely loud relative to every other cassette available, a fault that was made up for with its low weight — but only barely.
The new XC1090 is similar to the highly machined XX cassette, but also different. It uses a hollow, machined steel cluster to keep weight low, and caps this one-piece unit with an aluminum large cog, which is pressed onto the steel cluster.
This keeps weight very low, lighter than most Ti cassettes, while maintaining the durability of steel on the quickly-wearing cogs. But it doesn’t inherently keep noise down.
That job is given to a small elastomer that sits in between each cog, called “stealthings.” A special tooth profile allows the chain to contact these elastomers close to the derailleur, where there is no load, and then move onto the teeth as the cassette spins and load is applied by the chain. So the elastomers are a landing zone, minimizing noise while staying out of the way at the point at which wear occurs. There is no loss in efficiency and the elastomers take a very long time to wear out, according to SRAM’s testing. And, if they do eventually bite the dust, they can be purchased separately. Or, just run the cassette without them, they aren’t needed for the unit to function.
Does it work? I’ll go into more detail in the brief ride review later, but the short answer is yes. The new SRAM Red is the quietest group I’ve ever used, with nothing but the hiss of tires audible.
Brakeset: single-pivot size, dual-pivot power
The brakes are wholly redesigned as well, and step away from the classic dual pivot design in favor of a cam system similar to many of the expensive superlight brakes on the market. The design allows SRAM to maintain power and modulation while decreasing the weight. However, cams often have issues with changes in rim width, it changes the geometry of the whole system. Without more testing I can’t say whether this is an issue with the Red brakes.
The brakes can therefore be smaller, and more aerodynamic. They visibly integrate with the frame better, rather than sticking out well beyond the tube walls. Given that the front brake is on the forefront of your battle with the wind, such small changes can have an affect.
The quick release has been moved in-line with the cable, spring adjusters are recessed, and thanks to the cam design (they call it a “Force Multiplier Link) the whole setup is the size of a single pivot brake; three elegant features that also improve aerodynamics. The whole look is much sleeker than the current model.