Shimano Ultegra FC-R8100-P Power Meter Chainset Offering fantastic shifting and power measurement, the Shimano Ultegra FC-R8100-P Power Meter Chainset combines performance and data to ensure that every ride, race or training session can be optimised and enjoyed. The integrated, crank-based power meter measurement is accurate to +/-2%, and sends all the data to a bike computer via Bluetooth or ANT+. Readings are taken for both legs, so accuracy is increased and an insight into right and left balance is provided. The rechargeable battery is well protected from the elements so riding or racing in bad weather isn’t a problem. The HollowGlide outer chainring is super stiff for perfect shifts under heavy load, so changing gear halfway up a hill or during a hard effort is virtually instantaneous. Reworked teeth provide an increased contact area with a 12-speed chain for better efficiency and power transfer whilst the HollowTech II cold-forged hollow cranks are also extremely rigid to improve power transfer. A wide range of crank arm lengths and chainring configurations are available so that every rider can find the perfect match. Designed for use with Shimano HollowTech II bottom brackets.