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4iiii PRECISION Shimano Ultegra R8100 Single-Sided Crankset

Josh Matthew August 4, 2022


4iiii left side power on a Shimano Ultegra 12-speed groupset!

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4iiii PRECISION Shimano Ultegra R8100 Single-Sided Crankset

The 4iiii PRECISION Shimano Ultegra R8100 Single-Sided Crankset brings 4iiii left side power to Shimano’s new Ultegra 12-speed groupset! The 4iiii PRECISION 3 power sensor is accurate to +/- 1.0%, is lightweight and features an 800-hour battery life. The power meter is compatible with both ANT+ and Bluetooth SMART devices. This means you can use it with your favorite bike computer, smart phone or indoor training app.

Please note – this crankset measures left leg power only.



  • Chainrings: 50/34 | 52/36 | 53/39
  • Crank arm lengths: 165 mm | 170 mm | 172.5 mm | 175 mm


Tools Needed for Installation

You will need the following tools for installation of this product. You can purchase many of these commonly used tools in our store.

  • Shimano Crank Arm Cap Tool
  • 5 mm Allen key


Bottom Bracket: This power meter uses a 24 mm Shimano road spindle and must be used with a 24 mm Shimano bottom bracket.

Tip - If you already have a Shimano crankset on your bike, then this power meter will fit your bottom bracket perfectly as all Shimano cranksets use a 24 mm spindle.

Check Frame Clearance: Crank-arm based power meters like this one attach a sensor on the inside of the left crank arm. On some bikes, there is not enough room between the left crank arm and the chainstay for the sensor to clear the frame. Therefore, you should make sure you have at least 10 mm of clearance between the left crank arm and the chainstay - and that you don't have a bottom bracket mounted rear brake (used on some aero and TT bikes). The important area to measure is right in the middle of the crank arm. Please refer to the image below.

If you find that you have around 7-9 mm of clearance, what many people will do is simply install a 1 or 2 mm bottom bracket spacer (between the left crank arm and the frame), which will give them the clearance they need.

The clearance between the frame and left side power meter crank arm

4iiii Shimano Ultegra R8100 Power Meter Specs

Name4iiii PRECISION 3 R8000 Crankset
Bike TypeRoad
Location of Power MeasurementCrank arm
Left or Both Legs MeasuredLeft
Independent Left/Right MeasurementNo
InstallationMore involved (60 min. estimated)
Crank Arm MaterialAluminum
Communication ProtocolANT+ and Bluetooth SMART
Claimed Accuracy+/- 1.0%
Active Temperature CompensationYes
Battery TypeCR2032
Battery Life800 hours
Method of Cadence MeasurementAccelerometer
BCD110 4-bolt asymmetric
Spindle Size24 mm
Q Factor146
Warranty3 years

In the Box

  • 4iiii PRECISION Shimano Ultegra R8100 Single-Sided Crankset
  • CR2032 coin cell battery

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