The SRAM S975 BB30 Wireless Powermeter is SRM's most sophisticated SRAM Powermeter system to date. The S975 features SRAM's integrated, unidirectional-carbon crankarms and RED PG chainrings. For a rigid attachment, the S975 uses a CNC-machined aluminum spider. The result is the holy grail of Powermeters?a race day crankset that feels, looks, and acts like SRAM. You also maintain the hallmark weight savings of SRAM, with the complete Powermeter system weighing in around an ultra-light 804grams without the bottom bracket. The S975 Powermeter is extremely accurate, operating on the powerful ANT+ wireless system with an expressed accuracy of +/- 2%. The Powermeter is beast-approved as well, with a cadence range of 30-255 rpm and a wattage range from 0-4096 watts, it can handle any output?human or otherwise. This is achieved through the use of eight strain gauges. These are a system of sensors that detect any resistance and vary their output when experiencing applied force. The next step is for the strain gauges to convert this data into electrical resistance so it can be measured. The refinements to the system offer the stellar results that have already made the S975 Powermeter a hit with the pros.Choosing the SRAM S975 BB30 Powermeter provides you with several advantages over other systems. The weight savings and rigidity advantages of BB30 are obvious, but our favorite gain by far is that the S975 system is compatible with other 10- and 11-speed groupsets. Additionally, you can swap out the RED chainrings for Shimano, Rotor, SRAM and FSA Pro/Super Road chainrings. The SRM S975 Powermeter features a predicted 1400 hours of ride time per battery compared to the 400 hours of battery life of Quarq's S975 system. This means more time in the saddle, and less time worrying about your battery.The SRAM S975 Powermeter is compatible with various training software such as Training Peaks, SRM, and Strava. The S975 operates wirelessly with ANT+ Sport, and can be used seamlessly with SRM PowerControl 7 and PowerControl VI head units.The SRAM S975 BB30 Wireless Powermeter is available in four crankarm lengths from 170mm to 177mm, and is available in both standard and compact sizes. The S975 uses the SRAM BB30 bottom bracket.