Product Description QUARQ DFour DUB Power Meter Carbon Crank - With 4-arm spider for Dura Ace The QUARQ DFour DUB power meter carbon crankset is composed of two highly moulded carbon crank arms, a DUB axle and the DFour DUB power meter spider. It is your entry into the world of performance measurement - as long as you ride with your Road Dura Ace R9100, Ultegra R8000 or 105 R7000 chainrings. This light, strong and elegant crankset combines the clever DUB platform with the DZero power meter technology, which has been proven over many years. Information regarding the return of batteries and electrical equipment:Information on the return and disposal of used batteries and electrical equipment can be found here. Specifications:Application:Road, Triathlon & Time TrialType:power meter cranks (on both sides)Compatibility:2xChainring Mount:110 mm bolt circle, 4-arm asymmetricalTechnical Information:Series:DZero (DFour)Crank Arm Material:CarbonAxle Material:AluminiumCrank Arm Length:170.0 mm, 172.5 mm, 175.0 mmChainline:45.5 mmAxle Diameter:28.99 mmRecommended Bottom Bracket:all SRAM Road DUBTolerance:+/- 1.5%Point of Measurement:spiderPower Source:CR2032 lithium batteryBattery Life:approx. 200 hoursData Collected:power (dual-sided), cadence, torque, pedal stroke uniformityWaterproof:IPX7Data Transfer:ANT+, BluetoothCompatibility:expressly for Shimano Dura-Ace R9100 11-speed chainringsUltegra R8000 and 105 R7000 chainrings are compatible, but do not fit opticallyFeatures:carbon crank arms with DUB axle and 8-bolt interface, power meter spider, chainringstool-free battery replacement10K temperature compensationno cadence magnet required thanks to AxCad (multi-axis acceleration sensor)automatic recalibration while ridingeasy chainring change without recalibrationnatural carbon finishSRAM AXS app for zeroing, battery status, diagnostics and firmware updatesTechnology: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) and 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 and at specific locations in relation to the applied load. Strain gauges are used to measure this displacement and 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 and innovative scientific projects to discover subatomic particles. With a revised measurement loop, optimised strain gauge design, increased accuracy and the features of the Qualvin and SRAM AXS app, DZero represents the state of the art in power meter technology. You can choose between Bluetooth LE and ANT+ technology for data transfer. OmniCal™ 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. MagicZero™ Calibration takes place automatically during the ride. You don't need to pedal backwards or perform a manual calibration from your computer. Manufacturer Numbers:170.0 mm:00.3018.292.170172.5 mm:00.3018.292.172175.0 mm:00.3018.292.175Contents:1 x QUARQ DFour DUB power meter crankset1 x CR2032 batteries Manufacturer: SRAM LLC 1000 W. Fulton Market 4th Floor Chicago IL 60607 USA info@sram.com Distributor: SRAM Europe Sales and Services B.V. Paasbosweg 16 3862 ZS Nijkerk Netherlands info@sram.com