Train smarter and race harder with real left/right power data built directly into your cranks. The Shimano Ultegra FC-R8100-P integrates a dual-sided power meter into the proven Hollowtech II crankset — no bolt-on pods, no separate pedals, just accurate power numbers from every pedal stroke. At 175 mm with a compact 50-34T chainring combination, it suits a wide range of road riders from climbing specialists to all-rounders seeking training-grade data in a race-ready package.

Highlights

• True dual-sided measurement: strain gauges in each crank arm independently measure left and right leg output for genuine power balance, not an estimate.
• ±2.0% accuracy: active temperature compensation keeps readings consistent as conditions change.
• Integrated rechargeable battery: sealed Li-ion battery delivers 300+ hours of ride time between charges — no coin cells to replace, fully waterproof.
• ANT+ and Bluetooth LE: broadcasts simultaneously to cycling computers, smartwatches, and training apps.
• Hollowtech II construction: hollow-formed alloy crank arms and Hollowglide outer chainring deliver Ultegra-grade stiffness and crisp 12-speed front shifting.
• Compact gearing: 50-34T on a 110mm 4-bolt asymmetric BCD suits road racing, sportives, and hilly terrain.

Dual-sided power, built in

Unlike left-only systems that double a single reading, the FC-R8100-P places strain gauges in both the left and right crank arms. Each leg is measured independently, giving you true left/right power balance data alongside total power output and cadence. Active temperature compensation maintains accuracy across varying ride conditions, so your watts are reliable whether you are climbing in summer heat or sprinting on a cold morning.

No-fuss integrated battery

The sealed, rechargeable lithium-ion battery is integrated into the crankset body — fully waterproof and good for 300+ hours of riding between charges. Recharging is done via Shimano's EW-EC300 charge cable. Forget about buying coin cells or managing separate battery pods.

Ultegra performance, uncompromised

This is a genuine Ultegra R8100 crankset first and a power meter second. Hollowtech II hollow-formed alloy crank arms deliver the stiffness and efficient power transfer the series is known for. The Hollowglide outer chainring — partly hollow for weight savings — provides fast, precise front shifts across Shimano's 12-speed road groupset.

Compatibility & Fit

Designed for 2×12-speed Shimano road drivetrains. Hollowtech II spindle interface requiring a 24 mm Shimano bottom bracket (sold separately) compatible with 68 mm or 70 mm threaded bottom bracket shell widths. 110 mm 4-bolt asymmetric BCD. Chainline 44.5 mm. Q-factor 148 mm. Crank arm length 175 mm. Chainrings 50-34T. Pairs with any ANT+ or Bluetooth LE compatible cycling computer, watch, or training platform. Ensure a minimum 10 mm clearance between the left crank arm and your frame's chainstay before fitting.