SRAM Quarq DFour91 PowerMeter Spider Power Meter Chainsets

Product Description

This power meter spider features a CNC-machined aluminium construction, which makes it more than capable of withstanding all the intensity that's associated with long days in the saddle. Whether you're training for a road, triathlon, time trial or cyclocross event, this spider is developed to boost your training session with precise power measurement (dual-sided), cadence, torque & pedal stroke uniformity. Developed over the course of 10 years, this power meter spider has innovative features such as wireless two-channel data transmission via Bluetooth Low Energy (LE) & ANT+ or the Qalvin BLE app. If you already have a QUARQ power meter with an 8-bolt interface as a connection between spider & crank, you can upgrade it to DZero technology with the DFour 91 power meter spider. Item Top Features Continued: Power Source: CR2032 lithium battery Battery Life: Approx. 200 hours, tool-free battery change Data Collected: Power (dual-sided), cadence, torque, pedal stroke uniformity Waterproof: IPX7 Data Transfer: ANT+, Bluetooth Automatic or manual zero setting LED status display Standby after 10 minutes of inactivity, automatic restart by crank rotation No cadence magnet required thanks to Ax Cad (multi-axis acceleration sensor) 10K temperature compensation (programmed with over 10, 000 data points) Easy chainring change without recalibration Qalvin BLE app: installation, firmware updates, reset, battery status, system diagnostics Compatibility: Cranks:
- QUARQ ELSA RS (as of August 2014)
- QUARQ RIKEN AL (as of April 2015)
- QUARQ Prime Power Ready cranks (as of March 2016)
- QUARQ RIKEN R (as of July 2015)
- QUARQ DFour 91 power meters (as of 2017/18)
- SRAM Red Power Ready cranks (as of March 2016)
- SRAM Red BB386EVO standard cranks (as of March 2016)
- SRAM Red power meters (e Tap graphics as of January 2016)
- SRAM XX1 power meters (as of August 2014)
- not for QUARQ ELSA R Chainrings:
- for Shimano Dura Ace R9100 chainrings
- also compatible with Ultegra R8000 chainrings Technologies: QUARQ Operating Principle: The crankset forms the heart of your bike. Their only task is to convert the force of both legs into forward motion
- the perfect place to measure performance. Power meters calculate power by measuring torque (pedal force) & angular velocity (cadence). Power = torque x cadence. When you pedal, all parts of the bicycle drivetrain shift (bend) slightly under the load. Power meters are designed using FE analysis so that these displacements take place in a very controlled manner & at specific locations in relation to the applied load. Strain gauges are used to measure this displacement & thus calculate the applied torque. Reed switches are used to calculate the cadence. DZero: DZero is QUARQ's next generation power meter, named after the DZero Experiment, one of the most accurate & innovative scientific projects to discover subatomic particles. With a revised measurement loop, optimised strain gauge design, increased accuracy & the features of the Qualvin app, DZero represents the state of the art in power meter technology. You can choose between Bluetooth LE & ANT+ technology for data transfer. A simplified product line makes it easier for you to find the right power meter for your bike. Compatibility has been extended to include Boost 148 (52 mm chainline) for Mountain bikes & BB386EVO bottom brackets. Older QUARQ power meters can be upgraded to DZero technology with the DFour 91 power meter spider, provided they have the 8-bolt interface as a connection between the crank & the spider. Omni Cal: The power measurement depends on the choice of the right chainring. Change from a Road to a Time Trial chainring without sacrificing accuracy. No recalibration necessary. Power Balance: Shows the ratio of the generated power in the right drive stroke (first half) compared to the left drive stroke (second half). This means that you can pedal evenly with a 360 degree rotation.