Train and race with race-proven accuracy. The Shimano Ultegra FC-R8100-P is a dual-sided power meter built into a 175 mm Hollowtech II crankset, giving you true left and right leg power without sacrificing the stiffness, light weight and reliable shifting Ultegra is known for. This version ships without chainrings, so you can fit the ratio that suits your riding.

Highlights

• Dual-sided measurement: reads each leg independently for real left/right balance, not a mirrored estimate.
• ±2.0% accuracy: Shimano-rated precision across the calibration range — reliable for training zones and race pacing.
• 300+ hours battery life: integrated, waterproof, rechargeable Li-ion cell means no coin cells to swap or covers to lose.
• ANT+ and Bluetooth LE: pairs simultaneously with cycling computers, smartwatches and training apps.
• Hollowtech II construction: hollow forged aluminium arms keep the crankset stiff and light for efficient power transfer.
• No chainrings included: choose your own gearing — compatible with Shimano 12-speed road chainrings on the 110 mm 4-bolt asymmetric BCD.

Power you can trust

Strain gauges bonded into each crank arm measure the force from both legs independently, giving you accurate, repeatable numbers ride after ride. Shimano's active temperature compensation keeps the readings stable in cold morning starts and hot summer races alike. Detailed left/right metrics and force vector data are accessible through Shimano's Connect Lab platform to help you identify and correct imbalances in your pedal stroke.

Charge it and forget it

An integrated, fully sealed Li-ion battery means no exposed contacts and nothing for road spray to reach. A single charge lasts well over 300 hours of riding — months of typical use — and you top it up with the Shimano EW-EC300 charging cable (sold separately).

Connect to everything

Dual ANT+ and Bluetooth LE broadcasting lets you run the power meter simultaneously with a cycling computer and a training app, so Strava, Wahoo, Garmin, TrainingPeaks and the rest all receive your data in real time.

Compatibility & Fit

2 × 12-speed Shimano road drivetrains (Ultegra R8100 / Dura-Ace R9200 generation). 175 mm crank arm length. 24 mm Hollowtech II spindle — compatible with Shimano road bottom brackets such as SM-BBR60 (threaded BB shell) and SM-BB72-41B (press-fit). 110 mm 4-bolt asymmetric BCD accepts Shimano 12-speed road chainring combinations (e.g. 50/34T, 52/36T, 53/39T), sold separately. Q-factor 148 mm.