How Mechanical Power Meters Work ~
Mechanical Power meters (in cranksets, hubs, bottom brackets, or pedals) calculate power by measuring the torque (pedal force) and the angular velocity (cadence). Power = Torque x Cadence. When you press on the pedals, all parts of the bikes drivetrain displace (flex) slightly under the load. Power meters are designed using Finite Element Analysis to displace in a very controlled manner in specific locations in response to applied load. Strain gauges are used to measure the displacement and thus calculate the applied torque. Reed switches are used to calculate cadence. Quarq power meters use a proprietary strain gauge arrangement and precision digital circuitry to deliver high accuracy and low power consumption for optimal battery life.
New for 2014, but available now! A lighter, more accurate power meter completely integrated with the performance of Sram's new 22 speed group, SRAM RED-22. The sleek new geometry reduces system weight and delivers clearance for oversized frames and aerodynamic chainrings. The only visible power component is the low profile, all aluminum battery case. New stress flow lifts accuracy to +/- 1.5% and makes power measurement independent from chainring selection. Available in crank lengths from 162.5 through 177.5 .... $1999.99
Adaptable, lightweight and strong, and with the latest Quarq technology, ELSA 10R (to fit 10-speed chainrings) packs a four-pronged punch to elevate bike and rider performance. The subatomic spider houses integrated electronics, a CR2032 battery, LED indicator and visible ANT+™ ID. Power Balance™ captures left and right drive strokes. OmniCal™ gives you a choice of chainrings with no compromise on accuracy. Exogram™ Hollow Carbon crank arms by SRAM reduce weight and increase performance. With lengths of 162.5 through 177.5mm, ELSA will take any athlete to the next level .... $1999.99
The very dependable Riken 10R (to fit 10-speed chainrings) features durable, integrated electronics, a CR2032 battery and clearance for oversize bottom brackets. An LED indicator and visible ANT+™ ID streamline installation and operation. OmniCal™ means your choice of chainrings and no compromise on accuracy. Available in 170, 172.5, and 175 lengths, RIKEN can take you across the line in first place ... $1599.99
At the cutting edge of Power Metering since 2006, Quarq was purchased by leading parts manufacturer, SRAM, in 2011. The combination of precision Quarq metering and Sram's carbon technology has resulted in the stiffest, lightest, and most accurate tool available for precise power training. The S975 crankset uses SRAM's S900 carbon fiber crank arms and Sram Red chainrings. The smoothly integrated Quarq CinQo spider with strain gauges provides +/- 2% accuracy. Wireless ANT+ technology is compatible with several Garmin power receiving/display units including the Edge 800, 705, 305, and 500, as well as the CycleOps Joule 2.0. The calibration values are stored in the crank's CinQo unit so there is no need to recalibrate if you change head units. Coin-style battery (BA0124) lasts about 500 riding hours and is easily replaced.
Bottom Bracket specs: The S975 uses a Sram GPX cupset and is available to fit the 2 most popular bottom bracket shells currently in use: 68mm English threaded frames. The bottom bracket is not included (see below).
Size: The S975 is available 172.5 crankarms and compact (50x34) chainrings. Top-of-the-line Sram RED chainrings are included with each unit.
ANT+ crankset with CinQo power measuring unit and 2 chainrings .... $
Sram GXP bottom brackets, click here: Bottom Brackets
Available with ceramic or stainless steel bearings