Whether you're looking to take your training to the next level or you simply want a better way to measure energy expenditure, a power meter is your best bet. And the Power Cranks Ultegra Upgrade Kit are no exception. With our lightweight power sensors on a Shimano Ultegra crankarm, it's the perfect way to enter the power meter game. The development of Power Cranks began with our Human Performance Team looking at riders in realistic scenarios on the bike. Historically, power meters have been validated by two different methods—one is by measuring the produced torque by applying a static, linear load to a crankarm or chainring, while the second uses a power generating motor to pedal the bike. Well, cycling is neither static nor linear, and humans apply power much differently than a machine. So, we found that neither of these methods answer the "real-world" accuracy question. To get the best test for accuracy, in all types of riding scenarios, we built our own cycling treadmill, the WinMill, to measure power output to a known truth. This new benchmark lets us evaluate accuracy under all riding conditions—seated versus standing, various power and cadence levels, different weights, and a myriad of gear. This data acquisition process is our gold-standard for testing power meters, and through our testing and external validation from the Locomotion lab in Boulder, Colorado, Power Cranks have been proven to have the highest accuracy in real world scenarios (+/- 1.5%). The Power Cranks are also easy to live with, with class-leading temperature compensation firmware and waterproof enclosures. Calibration is only required during seasonal-type fluctuations in temperature, and the included wrench makes battery swaps a breeze. +/- 1.5% real-world accuracy tested on the WinMill and validated by the Locomotion Lab in Boulder, CO. Works with ANT+ and Bluetooth® devices. Easy set-up and diagnostics with the Specialized Power app. (iOS and Android versions available). Shimano 8000 generation Ultegra left-side power measurement. Right crankarm and chainring NOT included. Available in 170-175mm crankarm lengths.