Product Description QUARQ DFour DUB Power Meter Carbon Crank - With 4-arm spider for Dura Ace The QUARQ DFour DUB power meter carbon crankset consists of two highly molded 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 Trial Type: power meter cranks (on both sides) Compatibility: 2x Chainring Mount: 110 mm bolt circle, 4-arm asymmetrical Technical Information: Series: DZero (DFour) Crank Arm Material: Carbon Axle Material: Aluminium Crank Arm Length: 170.0 mm, 172.5 mm, 175.0 mm Chainline: 45.5 mm Axle Diameter: 28.99 mm Recommended Bottom Bracket: all SRAM Road DUB Tolerance: +/- 1.5% Point of Measurement: spider Power Source: CR2032 lithium battery Battery Life: approx. 200 hours Data Collected: power (dual-sided), cadence, torque, pedal stroke uniformity Waterproof: IPX7 Data Transfer: ANT+, Bluetooth Compatibility: expressly for Shimano Dura-Ace R9100 11-speed chainrings Ultegra R8000 and 105 R7000 chainrings are compatible, but do not match optically Features: carbon crank arms with DUB axle and 8-bolt interface, power meter spider, chainrings tool-free battery replacement 10K temperature compensation no cadence magnet required thanks to AxCad (multi-axis acceleration sensor) automatic recalibration while riding easy chainring change without recalibration natural carbon finish SRAM AXS app for zeroing, battery status, diagnostics, and firmware updates Technology: QUARQ Operating Principle The crankset forms the heart of your bike. Its 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, optimized 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: 00.3018.292.170 172.5 mm: 00.3018.292.172 175.0 mm: 00.3018.292.175 Contents: 1 x QUARQ DFour DUB power meter crankset 1 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