This Truvativ X0 GXP 2.2 10-Speed Crankset uses carbon fiber like the top shelf XX crank, but there are a few differences. Unlike the XX crank, there"s no alloy spine connecting the threaded pedal insert and the crank/spindle connection. SRAM engineers figured out a way to eliminate it, instead using a stiff structural foam core inside the composite skin. Don"t think for a second that it"s weaker; part of SRAM"s goal for XO was to make it burly enough to handle the rigors of all-mountain riding. Another difference is that this XO crankset uses an aluminum spider where the XX spider is an integral part of the carbon crankarm assembly. While it"s a few grams heavier, the XO system allows you to remove the spider if you want to change from two to three rings or vice versa. As is, this 2x10 setup has a bolt circle diameter of 80/120mm. Of course, it"s an exclusive measurement, but for the chainring tooth combinations SRAM wanted to offer, it optimizes the stiffness of the rings. And stiffer chainrings mean quicker, more precise shifts.Not only did they design their own optimized bolt circle diameters, but they re-engineered the shift ramps, pins, and cut outs on the outer chainring. On most chainrings these days, there are two sets of ramps and two drop points where the chain can get lifted or dropped quickly and under pressure. This means that twice each pedal revolution you"ll hit these spots, so the shifting can be iffy if you shift at any other time. You"ve probably experienced this with the pause and clunk and sometimes smooth movement on other crank systems. SRAM"s X0 outer ring allows perfect shifts just about all the way around the crank. They call this X-Glide. Another improvement stems from having only two rings. From the small ring, the chain can only go up, from the big ring, only down. With this in mind, each ring can be shaped specifically for its more focused purpose. The Truvativ X0 GXP 2.2 10-Speed Crankset has Clear Coated Carbon fiber arms with a...