4iiii PRECISION Shimano XT M8100/8120 Power MeterMarch 19, 2023
$334.99 – $384.99
4iiii power for your Shimano XT M8100/8120/8130 crankset!
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 800 hours of battery life and is compatible with both ANT+ and Bluetooth SMART devices.
Key Product Details
This 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. See Compatibility tab for more information.
This 4iiii power meter measures left leg power and doubles the value to account for both legs (assumes both legs are generating the same force).
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.
Affordable, accurate to within +/- 1.0%, lightweight at only 9 grams of added weight, 800 hours of battery life (PRECISION 3), CR2032 user-replaceable battery, ANT+ and Bluetooth compatible, easy to install, 3-year warranty. See Specs tab for more information.
Advice From Our Staff:
4iiii left side crank arms are some of our best-selling units. They are affordable and easy to install. The one consideration is they only measure left leg power compared to some other power meters that measure power from both legs (those version usually cost more however).
Options For This Power Meter
- Versions: PRECISION 2 | PRECISION 3 (see above for PRECISION 3 differences)
- Crank arm lengths: 170 mm | 175 mm
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.
4iiii PRECISION Shimano XT M8100/8120 Specs
Name 4iiii PRECISION XT M8100/8120 Bike Type MTB Location of Power Measurement Crank Arm Left or Both Legs Measured Left only Independent Left/Right Measurement No Installation Easier Crank Arm Material Aluminum Communication Protocol ANT+ and Bluetooth SMART Claimed Accuracy +/- 1.0% Automatic Temp. Compensation Yes Weight 9 grams (added weight) Battery Type CR2032 coin cell Battery Life Version 2: 100 hours / Version 3: 800 hours Method of Cadence Measurement Accelerometer Warranty 3 years
In the Box
- 4iiii PRECISION Power Meter
- CR2032 coin cell battery
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
Common Questions and Answers
Question: How do I determine what length my current cranks are so I can make sure I get the same size?
- Your crank arm length should be printed or stamped on the inside of the left crank arm, usually near the pedal end.
John Stachlewicz (verified owner) –
Installed the 4iii Precision 3 power meter on my Specialized Epic EVO. Went with the 3 mainly for the thinner profile to make sure there was plenty of clearance, which there was. I’ve been able to get a few rides in now and I’m happy to report the 4iii has been rock solid! I have zero issues with drop outs or disconnects even i coast for a bit. The power meter numbers are in line with what I would expect to see.
Installation was super simple. I did order the Shimano crank arm cap tool just for the added convenience
Power Meter City –
Hi John. Thank you for this amazing review on your new 4iiii PRECISION Shimano XT M8100/8120 Power Meter. We hope you will continue to enjoy them! Please let us know if there is anything else we can help you with!