4iiii PRECISION 3+ Shimano GRX RX810 Power MeterDecember 8, 2023
4iiii’s PRECISION power meter combined with Shimano’s GRX RX810 groupset
4iiii PRECISION 3+ Shimano GRX RX810 Power Meter
Introducing the all new 4iiii PRECISION 3+ Shimano GRX RX810 Power Meter. 4iiii has combined their patent pending 3-D tri-axial strain gauge technology, measured at +/- 1.0% accuracy, with Shimano’s GRX RX810 groupset. The result is one of the lightest, most affordable and most accurate direct force power meters available for gravel and adventure riders.
The 4iiii power meter measures left leg power and doubles this value to determine your total power. This left-only design allows for a power meter that is affordable, lightweight and easy to install. The power meter adds only 9 grams to your crank arm and is installed in about 10 minutes. In addition, the PRECISION is compatible with both ANT+ and Bluetooth SMART devices. This means you can use it with your favorite bicycle computer, watch or smart phone.
Key Product Details
This power meter is compatible with Shimano GRX RX810 and RX600 cranksets. 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 GRX RX810 PRECISION 3+!
The all new 4iiii GRX RX810 PRECISION 3+ power meter features the following improvements over the version 2:
- Apple Find My which allows you to always know where your bike is!
- 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, 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
Crank arm lengths: 170 mm | 172.5 mm | 175 mm
Other Versions to Consider
Dual-Sided GRX RX810 Crankset: We also sell the 4iiii PRECISION PRO Shimano GRX RX810 Dual-Sided Power Meter which is a complete crankset. It is more expensive, however it measures power from both legs.
Right Side GRX RX 810 Crankset: Some bike frames cannot fit a left side power meter due to clearance issues with the chainstay. In these situations, we offer the 4iiii PRECISION Shimano GRX RX810 Right Side Power Meter. It allows you to quickly and easily add power to the right side of your crankset where clearance and compatibility issues don’t exist.
Crankset: The 4iiii power meter is compatible with all Shimano GRX cranksets including GRX RX600.
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 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 GRX RX810 Specs
|Name||4iiii PRECISION 3+ GRX RX810|
|Location of Power Measurement||Crank Arm|
|Left or Both Legs Measured||Left only|
|Independent Left/Right Measurement||No|
|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||800 hours|
|Method of Cadence Measurement||Accelerometer|
In the Box
- 4iiii PRECISION Shimano GRX RX810 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: What is the difference between the 4iiii PRECISION 2 and PRECISION 3+?
- The P3+ was introduced in early 2022 and offers several benefits over the P2 model. Please see our article for more information: 4iiii PRECISION 2 vs. PRECISION 3+ Comparison.
Question: Is this power meter available in a GRX 600 version?
- No, this power meter only comes in a GRX 810 version. This is because, the backside of the GRX 600 crank arm is not flat, rather it has ridges, and therefore a sensor can’t be attached to it. However, this GRX 810 power meter also fits on Shimano GRX 600 cranksets.
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.
Question: Do you also stock new chainrings for my Shimano GRX crankset?
- Yes, we have several Shimano GRX Chainrings to choose from, including 1x or 2x and round or oval.