SRAM's Rival AXS left Arm Power Meter offers reliability and accuracy, packaged in a sophisticated design. The most discerning of road cyclists can take advantage of the long, 400-plus-hour battery life and proven Quarq reliability and accuracy to calculate total watts and delve into the minute details of tough training sessions. The smooth integration of the power meter, which is contained within the DUB spindle, makes for a design that fits more bikes than ever, and we like that it's a simple power meter upgrade option at a value. It's durable enough to stand up to the rigors of training and riding, and it weighs in at just under 40 grams heavier than a standard crankset.