Because the latest and greatest mtb frames are embracing the BB30 bottom bracket shell, we offer the SRAM XX 2x10 crank (yes, XX and 2x10 next to each other is redundant) with a 30mm thru-axle/bottom bracket spindle in addition to the XX crank with a more traditional thru-axle designed for the GXP bottom bracket. This XX crank with the 30mm pipe will work with either SRAM's BB30 bottom bracket or SRAM's PressFit 30 bottom bracket. This is the same crankset, with a 49.5mm chainline as the standard, just with a 164mm Q-factor and 30mm diameter spindle. We could go on and on about the benefits of BB30, but if you don't have a frame with the BB30 shell, you have no need for it. Stiffer, lighter, sealed better. The crankarms are foam core inside an aluminum exoskeleton inside a carbon shell. There are two different chain ring combinations, all with a 120mm outside bolt circle diameter and 80mm inside bolt circle diameter.39/26 or 42/28 -- they each have a 3:2 ratio. The big ring bolts thread through the arm into the chain ring. The small ring bolts into the spider. The rings are cut from 6mm wide 7075-T6 aluminum. Stiffer than other rings, yet still really light. SRAM developed a new ramp/pin/cutout pattern for faster, more confident shifting under full power. It's called X-Glide and doubles the number of ideal shift points during a pedal revolution. SRAM recommends their 10-speed road chains, 1090 and 1090R to mate this crank to their XX cassettes. The crank comes with either 170 or 175mm crankarms. The color of the crankarms is Black, the chain rings are Tungsten Grey and Silver. Claimed weight of the SRAM XX 42/28 crankset with the BB30 bottom bracket is 694g, and the 39/26 has a claimed weight at 670g.Click here to save when you purchase an XX build kit.