4iiii PRECISION PRO Shimano GRX RX810 Dual-Sided Power MeterJune 5, 2023
$769.99 – $836.99
The first and only dual-sided Shimano’s GRX power meter crankset!
4iiii PRECISION PRO Shimano GRX RX810 Dual-Sided Power Meter
The 4iiii PRECISION PRO Shimano GRX RX810 Dual-Sided Power Meter combines 4iiii’s patent pending 3-D tri-axial strain gauge technology with Shimano’s GRX RX810 crank. The result is an accurate, lightweight and highly reliable power meter crankset that is capable of tacking the most grueling workouts or races.
The dual-sided 4iiii GRX crankset features independent left/right power measurement. With a power sensor located on the inside of both crank arms, the power meter can measure the forces generated by each leg individually.
The 4iiii is also extremely lightweight, adding approximately 20 grams to the Shimano GRX crankset. The power meter is compatible with both ANT+ and Bluetooth SMART devices and is accurate to +/- 1.0%.
Key Product Details
This power meter is compatible with Shimano GRX groupsets and uses a 24 mm spindle and fits Shimano 24 mm bottom brackets. If you already have a GRX crankset on your bike, it will be an easy swap. See Compatibility tab for more information.
This 4iiii power meter has a power sensor on both crank arms and measures power from both legs. It is also able to measure your left vs. right leg power.
Dual-leg power measurement, can measure left vs. right leg power, accurate to within +/- 1.0%, lightweight at only 20 grams of added weight, 100 hours of battery life, CR2032 user-replaceable battery, ANT+ and Bluetooth compatible, 3-year warranty. See Specs tab for more information.
Advice From Our Staff:
If you are looking for a dual-sided Shimano GRX power meter crankset, this is for you. In fact, it’s the only dual-sided OEM GRX crankset with power.
Options for the 4iiii GRX Dual-Sided Power Meter
Crank arm lengths: 170 mm | 172.5 mm | 175 mm
Chainring size: 40T | 42T | 48/31T
Other Versions to Consider
Single-Sided GRX RX810 Crankset: We also sell the 4iiii PRECISION Shimano GRX RX810 Right Side Power Meter which is a right side crank arm only. It is more affordable, but only measures power from the right leg.
Bottom Bracket: This power meter uses a 24 mm Shimano spindle and must be used with a 24 mm Shimano bottom bracket.
Tip - If you already have a Shimano GRX RX810 or RX600 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.
4iiii PRECISION PRO Shimano GRX RX810 Dual-Sided Specs
|Name||4iiii PRECISION 2 GRX Dual Side|
|Location of Power Measurement||Crank Arm|
|Left or Both Legs Measured||Both|
|Independent Left/Right Measurement||Yes|
|Installation||More involved (60 min. estimated)|
|Crank Arm Material||Aluminum|
|Communication Protocol||ANT+ and Bluetooth SMART|
|Claimed Accuracy||+/- 1.0%|
|Automatic Temp. Compensation||Yes|
|Weight||20 grams (added weight)|
|Battery Type||CR2032 coin cell|
|Battery Life||100 hours|
|Method of Cadence Measurement||Accelerometer|
In the Box
- 4iiii Power Meter with chainring
- 2 CR2032 coin cell batteries
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.
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.
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