With several years of development working closely with professional teams you can expect extreme accuracy from Shimano\\\'s first fully integrated power meter HollowTech II 11-speed Dura-Ace chainset. The integrated bottom bracket seal design uses a wider minimal bearing interface placement and larger axle diameter for increased stiffness and efficiency. Shimano lead the industry in refined alloy crank design and the R9100 is the cold forged hollow crank arm manufacturing process at its most evolved increasing rigidity, reducing weight, and improving strength. On this chainset accurately calibrated strain gauges are integrated inside both left and right crank arms, this provides a stable measurement system through rotation from both sides for extremely precise data. Key Features: +/-2% accuracy of strain gauge measured power. Bluetooth and ANT+ with wireless firmware update and data acquisition system. Easily rechargeable integrated battery with fully waterproof reliable electric system.