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4iiii PRECISION Shimano XT M8100/8120 Power Meter

Josh Matthew June 26, 2022


4iiii power for your Shimano XT M8100/8120/8130 crankset!

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4iiii PRECISION Shimano XT M8100/8120 Power Meter

The 4iiii PRECISION Shimano XT M8100/8120 Power Meter brings 4iiii power to your Shimano XT crankset! The 4iiii power meter is a left side crank arm-based power meter. You simply install it in replace of your currently left side crank arm and you are powered up! The 4iiii will take the power that is generated by your left leg and double it in order to determine your total power output.

The 4iiii is a highly accurate power meter. It’s built-in accelerometer can measure precise cadence data and it has 3D power meter technology capable of measuring tri-axial strain. The result is a power meter that is accurate to +/- 1.0%.

The 4iiii Shimano XT M8100/8120 Power Meter features 100 hours of battery life and is compatible with both ANT+ and Bluetooth SMART devices.


New 4iiii XT 8100/8120 PRECISION 3!

The all new 4iiii XT 8100/8120 PRECISION 3 power meter features the following improvements over the version 2:

  • 800 hours of battery life – the longest coin cell battery life in a power meter on the market!
  • Sleeker, slimmer profile making most incompatibility issues a thing of the past.
  • Stronger antenna for even better connectivity.
  • Indicator light for battery life, successful zero-offset and when the unit has been turned on.


4iiii PRECISION Shimano XT Power Meter Highlights

Most Affordable DFPM

The 4iiii PRECISION is one of the most affordable, ready to ride direct force power meters available.

High Level of Accuracy

The PRECISION is accurate to within +/- 1.0%. This compares to average accuracy of +/- 1.0-2.0% for most other power meters.

Lightest Power Meter

At only 9 grams of added weight, the PRECISION 3 is the lightest power meter you can buy!

Easy to Install

Installation is a breeze. Just swap it out for your current left-side crank arm and you’re ready to ride! Installation takes minutes…not hours.

ANT+ & Bluetooth SMART

The power meter transmits data via both ANT+ and Bluetooth SMART so you can use it with a wide range of devices.


  • Versions: PRECISION 2 | PRECISION 3 (see above for PRECISION 3 differences)
  • Crank arm lengths: 170 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


Crankset: The 4iiii power meter is compatible with XT M8100/8120/8130 cranksets. It is also compatible with all other Shimano x100/x120/x130 series MTB cranksets such as the XTR M9100/M9120/M9130 or the SLX M7100/7120/7130.

It is not compatible with x000 series cranks such as the XTR M9000, XT M8000 or SLX M7000.

Check Frame Clearance: Crank-arm based power meters 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 for the PRECISION 2 and 8 mm of clearance for the PRECISION 3. Also, make sure 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 your clearance is close but not quite sufficient, what many people will do is simply install a 1 or 2 mm bottom bracket spacer (between the left crank arm and the frame). This should provide you with the clearance you need.

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

4iiii PRECISION Shimano XT M8100/8120 Specs

Name4iiii PRECISION XT M8100/8120
Bike TypeMTB
Location of Power MeasurementCrank Arm
Left or Both Legs MeasuredLeft only
Independent Left/Right MeasurementNo
Crank Arm MaterialAluminum
Communication ProtocolANT+ and Bluetooth SMART
Claimed Accuracy+/- 1.0%
Automatic Temp. CompensationYes
Weight9 grams (added weight)
Battery TypeCR2032 coin cell
Battery LifeVersion 2: 100 hours / Version 3: 800 hours
Method of Cadence MeasurementAccelerometer
Warranty3 years

In the Box

  • 4iiii PRECISION Power Meter
  • CR2032 coin cell battery

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