For all of you Dura-Ace fans out there, Specialized have combined their extremely light power sensors with a Shimano Dura-Ace crankset to give you the most accurate and precise power meter available.
The development of Power Cranks began with their 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. Specialized 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, Specialized built their own cycling treadmill, the WinMill, to measure power output to a known truth. This new benchmark lets them 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 their gold-standard for testing power meters, and through 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 Dual-Sided S-Works Power Cranks utilise separate strain gauge systems to individually measure the effort produced by each leg. This maximises the accuracy of your total power numbers, plus it helps you to better understand your performance as fatigue increases and when you're recovering from injury. With class-leading temperature compensation firmware and waterproof enclosures, Power Cranks are easy to live with. Calibration is only required during seasonal-type fluctuations in temperature, and the included wrench makes battery swaps a breeze.