Round chainrings are standard because, well, they're standard, but they don't actually match the changing power output of your legs through a pedal stroke. Absolute Black's SRAM Oval Chainring's oblong shape makes pedaling easier in hard spots and steadier in easy spots, so you can keep a constant and smooth cadence without having to deal with dead up-strokes and leg-crushing down-strokes. This makes it easier to nail down the highly efficient circular pedaling motion that's we're all after, and improves traction by eliminating the wheel slip that happens during hard down-strokes on loose terrain.