Shimano Ultegra R8100 Power Crank Arms Only

Description

The Shimano Ultegra 8100 Power Crank Arms bring dual-sided power measurement to the Ultegra 8100 groupset — delivered as crank arms only, so you can pair them with your existing chainring and build out your setup on your own terms. Accuracy sits within ±1.5%, and left-right balance data gives you a clearer picture of how your effort is actually distributed across each pedal stroke.

These arms use Bluetooth and ANT+ connectivity, making them compatible with a wide range of head units and training platforms. The battery is rated for over 300 hours of ride time and is waterproof, so charging interruptions and weather are rarely going to be your concern. Zero-offset calibration is straightforward — something you’ll appreciate when you’re standing in a parking lot before a ride rather than fiddling with software at home.

Shimano Ultegra 8100 Power Crank Arms Specs at a Glance

• Measurement: Dual-sided power, ±1.5% accuracy
• Connectivity: Bluetooth and ANT+
• Battery life: Over 300 hours, waterproof
• Crank arm lengths: 160mm, 165mm, 170mm, 172.5mm, 175mm
• Compatibility: Shimano 12-speed groupsets (arms only — chainring sold separately)

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