Quarq has been the innovator and leader in crank based power meters. Their robust design was one of the first to have easy calibration and tool free battery replacement. Quarq power meters now come in an array of options in both carbon and aluminum for road and mountain bikes. You may also upgrade your existing SRAM crankset with the addition of a Quarq power meter spider, without replacing the entire crankset or chasis. With an array of crank lengths and ring choices you can select the Quarq power meter that meets your exact specifications. Completely waterproof, accurate to within 1.5%, both Bluetooth and Ant+ connectivity, and featuring active temperature compensation a Quarq has all the features cyclists demand.