Skip to main content
Home » 4iiii Power Meters » 4iiii PRECISION 3+ Shimano GRX RX810 Power Meter
A black 4iiii PRECISION 3+ Shimano GRX RX810 Power Meter with the Apple Find My Logo.

4iiii Power Meters

4iiii PRECISION 3+ Shimano GRX RX810 Power Meter

Niel Ubod August 20, 2025
5.00 out of 5 based on 22 customer ratings
(22 customer reviews)

$399.99

4iiii’s PRECISION power meter combined with Shimano’s GRX RX810 groupset

Clear selection
Free Shipping over $75

We offer free shipping on orders in the U.S. of $75 or more.

We also ship fast! In stock orders placed before 4 pm PT almost always ship the same day!

Easy Returns

Shop with confidence! We offer a simple, 30-day policy where you can return new, unused items for a refund, exchange or store credit.

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

Compatibility:

The 4iiii power meter is compatible with all 11- and 12-speed Shimano GRX cranksets including GRX 600, 610, 810 and 820. See Compatibility tab for more information.

Power Measurement:

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.

Key Features:

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.

Compatibility

Crankset: The 4iiii power meter is compatible with all 11- and 12-speed Shimano GRX cranksets including GRX 600, 610, 810 and 820.

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.

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

4iiii PRECISION Shimano GRX RX810 Specs

Name4iiii PRECISION 3+ GRX RX810
Bike TypeGravel
Location of Power MeasurementCrank Arm
Left or Both Legs MeasuredLeft only
Independent Left/Right MeasurementNo
InstallationEasier
Crank Arm MaterialAluminum
Communication ProtocolANT+ and Bluetooth SMART
Claimed Accuracy+/- 1.0%
Automatic Temp. CompensationYes
Weight9 grams (sensor) | 208 grams (170 mm)
Battery TypeCR2032 coin cell
Battery Life800 hours
Method of Cadence MeasurementAccelerometer
Warranty3 years

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.

22 reviews for 4iiii PRECISION 3+ Shimano GRX RX810 Power Meter

  1. Perry Taubman (verified owner) –

    This is my third 4iii power meter. I put it on my Specialized Diverge gravel bike. It works great and for the price I don’t think you can beat it. If you haven’t trained with a power meter before you should buy it. It’s a real game changer.

    • Power Meter City –

      Thanks for the awesome review, Perry! We’re thrilled to hear your third 4iiii power meter is working great on your Diverge. Totally agree—once you start training with power, it’s a game changer. Appreciate your support and happy riding!

  2. Matthew Thomas (verified owner) –

    As you can see.. This is my second one for yet another gravel bike. This time a Specialized Crux, and guess what? It fits perfectly! Great service, communication, and fast shipping from Power Meter City. 🙂

    • Power Meter City –

      Awesome! We’re thrilled to hear the power meter fits your Specialized Crux perfectly. Thanks for your continued support—we truly appreciate it! Enjoy the ride, and let us know if you ever need anything.

  3. Matthew Thomas (verified owner) –

    I like then simplicity of this power meter as I have the Ultegra version on my road bike. Thank you Power Meter City for the prompt shipment! Also, fits perfectly on my Cervelo Aspero with plenty of clearance. 🙂

    4iiii power meter clearance from a Chainstay.

    • Power Meter City –

      Thank you for your great feedback, Matthew! We’re glad to hear you appreciate the simplicity of the power meter and that it fits perfectly on your Cervelo Aspero. It’s always rewarding to know our customers are satisfied with their purchases. We appreciate your kind words about our prompt shipping, and if you have any questions or need assistance in the future, feel free to reach out. Enjoy your rides!

  4. Stuart (verified owner) –

    I have just built up a Ritchey Outback with GRX 820 and wanted a simple way to track power. There is plenty of room with this frame to clear the power meter cover and the instructions on this website made it easy to check before buying. My other bikes all have rotor power meters with 30mm spindles, the outback uses a BSA bottom bracket and didn’t want to compromise bearing size so this was an easy choice. It was easy to install and connect to my Karoo and so far I’m very happy with the perfomance that seems to track pretty closely to my other power meters

    A light blue Richey Outback with a 4iiii PRECISION 3+ GRX RX810 Power Meter on a 1x Shimano drivetrain.

    • Power Meter City –

      Thanks for sharing your experience, Stuart! It’s great to hear the setup went smoothly. The Ritchey Outback is a fantastic choice, and pairing it with the GRX 820 and power meter sounds like an ideal build for versatility and performance. We’re glad the power readings are consistent with your other bikes, and we hope you enjoy many rides with your new setup. Safe rides!

  5. Kevin B (verified owner) –

    First power meter ever for me and super happy I chose the 4iii for my grx810 crankset on my canyon grizl cf slx di2. Power meter city has great customer service and got back to all my questions about clearance in a very timely manner. Setup was extremely easy and it connected to my garmin 840 within minutes. Nothing but great things to say about the 4iii and power meter city.

    • Power Meter City –

      Thank you so much, Kevin. Looks like you are enjoying your new 4iiii power meter. We are here if there is anything else we can help you with!

  6. Thomas Mays (verified owner) –

    Finishing Touch for my TIME ADHX

    The meter works perfectly and enhanced my riding very fast as I can put out a much more consistent effort on long rides

    A 4iiii Precision 3+ Pod clearing a chainstay on a bike.

    • Power Meter City –

      Thanks for the picture of the frame clearance for this setup, Thomas. We’re glad this is working well for you. Enjoy the ride!

  7. Rpratt (verified owner) –

    The 4iiii GRX RX810 power meter has worked flawlessly, once I replaced the battery that it came with. The power meter reliably connects to my Garmin 1040 and calibrates consistently. The power meter fits comfortably between the crank arm and the frame of a Canyon CF SLX Grizl gravel bike. This was the third power meter purchased from Power Meter City. I will shop at Power Meter City for future power meter purchases, too.

    • Power Meter City –

      Thank you so much, Rpratt! Looks like you are enjoying your new 4iiii 3+ power meter. Your feedback inspires us to continue delivering excellence. We can’t wait to have the opportunity to serve you again soon! Ride safe!

  8. Vince Witkowski (verified owner) –

    Best bang for your buck! Excellent quality and rock solid performance for such an affordable power meter. Batteries last longer than expected and even more so if you use lithium ones. As always, top notch service from Power Meter City as well.

    • Power Meter City –

      Thank you so much! We really appreciate this. Good luck on future rides with your new power meter!

  9. Vince W (verified owner) –

    Best bang for your buck! Works flawlessly and still going strong after heavy use. Use lithium batteries for extended use! As always, excellent service from Power Meter City!

    • Power Meter City –

      Awesome! Thank you, Vince! We are here if there is anything else we can help you with!

  10. PatrickZ (verified owner) –

    Arrived quickly, install and set up was a breeze. Fits my Canyon Grail with plenty of clearance. Paired with Wahoo Bolt easily. Only thing I wish it came with was some better spring weather… I want to go ride! (*20 mph headwinds are no joke, but I knew how much power I was using which is so cool)

    • Power Meter City –

      That’s true Patrick 🙂 We’ll get there! We hope you will enjoy your new 4iiii power meter! Please let us know if there is anything else we can help you with! Thank you!

  11. Fernando (verified owner) –

    Arrived on time as promised. Working great and easy to install. Bike is a Canyon Grizl 7 and plenty of space left, good fit. I am glad I bought it.

    4iiii PRECISION Shimano GRX RX810 Power Meter showing chainstay clearance

    • Power Meter City –

      Thank you for this awesome review, Fernando! We hope you will continue to enjoy your new power meter and we are here if there is anything else we can help you with! Ride safe!

  12. Edward Inocentes (verified owner) –

    Very happy with my 4iiii PRECISION GRX RX810 that I’ve been using since late Jan 2022. It was very easy to set up – detected and paired with my Garmin 830. Used it extensively including under varying gravel conditions.

    This was my first order with Power Meter City. Happy with the fast shipping turnaround time.

    4iiii PRECISION Shimano GRX RX810 Power Meter on a Shimano GRX 2x crankset

    • Power Meter City –

      Awesome! Nice setup, Edward! Thank you for this kind review on your new 4iiii GRX power meter. Please let us know if there is anything else we can help you with!

  13. Rod Te Whatu (verified owner) –

    Great communication and service. Product arrived in NZ within 7 days of being dispatched which was pretty quick. Easy installation and set up. I’m very happy!

    • Power Meter City –

      Thank you so much for this kind review, Rod! We hope you will continue to enjoy your new 4iiii power meter! We are here if there is anything else we can help you with! Ride safe!

  14. Andrew littleton (verified owner) –

    Power meter meter shipped same day, and product was was as advertised.

    • Power Meter City –

      Thank you, Andrew! We really appreciate it! If there is anything else we can do, please let us know! Ride safe!

  15. David Williams (verified owner) –

    The power meter works flawlessly and was simple to install. The service and delivery from Power Meter City was exceptional. Less than a week to deliver to Brisbane, Australia.

    • Power Meter City –

      Awesome David! That was fast than expected! We hope you will enjoy your new power meter. We are here if there is anything else we can help you with!

  16. Kim Hyunseung (verified owner) –

    My second PM I bought here and I am very satisfied. Works well, perfectly fits with my Giant Revolt. Thanks for caring, have a nice day!

    • Power Meter City –

      Thank you for the loyalty and kind review Kim – we really appreciate it! We hope you will enjoy your 2nd power meter (Good choice BTW!) Let us know if there is anything else we can do! Ride safe!

  17. Takaaki Takuma (verified owner) –

    This is the third Power Meter by me. One STAGES and two 4iiii. 4iiii is awesome PM. High stability and accuracy, water registance. If I buy one more PM again, absolutely will chose 4iiii.
    Power Meter City is reliable shop, because quick shipping and send me emails when I need.

    • Power Meter City –

      Hi Takaaki. Thanks for this kind review – we really appreciate it. We hope you will continue to enjoy your new power meter. Please let us know if there is anything else we can do!

  18. Trevor (verified owner) –

    As all the other reviews say… great customer service. Arrived within a week in Australia, faster than what local post could achieve….
    Easy to install, calibrate and start using. Great communication from ordering, shipping through to delivery… and excellent support followup as well.
    Definitely recommend purchasing from Power Meter City!

    • Power Meter City –

      Hi Trevor. Thanks for this kind review! We are glad you finally have your power meter – good luck on your future rides. We are here if there is anything else we can do!

  19. Nerio (verified owner) –

    Excellent product, and superb customer service from Powermetercity. Arrived within 3 business days (earlier than expected) even despite shipping all the way to Singapore during the current pandemic.

    Purchasing this has been a hassle free experience, and all my questions were answered promptly by using the chat feature on the site. Furthermore, Powermetercity is the only place which had this in stock.

    Lastly, the product itself has been faultless. Works really well, great app support, and does the job!

    • Power Meter City –

      Nice! Thanks for this Nerio. We are glad it came fast despite the current situation. Good luck on your future rides! We are here if there is anything else we can do!

  20. Thomas Coleman (verified owner) –

    Good price and good quality equipment

    • Power Meter City –

      Hi Thomas. Thanks for this awesome review on your 4iiii PRECISION Shimano GRX RX810 Power Meter. We hope you will continue to enjoy them and we are here if there is anything else we can do!

  21. Philip Gray (verified owner) –

    This was my first purchase from Power Meter City and I was not disappointed! Super fast shipping, I was installing the power meter to my bike in less than a week after purchase, which is pretty good as I am in New Zealand. Great communication and follow up emails offering post purchase support, if only more companies offered this level of customer care!

    • Power Meter City –

      Hi Philip. Thanks for this kind review on your 4iiii PRECISION Shimano GRX RX810 Power Meter. Good choice for your first power meter! We hope you will continue to enjoy them! We also want to thank you for being a great customer! Let us know if there is anything else we can do!

  22. Michael Brannon –

    This is my 2nd 4iiii power meter purchased from power meter city. I had a problem with this model, and Josh from pmc shipped me a new one out, pronto! PMC has the best customer service that I’ve dealt with recently. I’ll definitely be purchasing all my power meters from Power Meter City

    • Power Meter City –

      Hi Michael. We really appreciate this and thank you for being a great customer. We hope you will enjoy your new 4iiii PRECISION Shimano GRX RX810 Power Meter. Please let us know if there is anything else we can do!

Add a review

The maximum upload file size: 5 MB. You can upload: image, audio, video, document, spreadsheet, interactive, text, archive, code, other. Links to YouTube, Facebook, Twitter and other services inserted in the comment text will be automatically embedded. Drop file here

Q&A

Have a question about this? Ask the staff.

4 Questions

OTHER CUSTOMERS ALSO VIEWED

THIS PRODUCT IS FREQUENTLY BOUGHT WITH

Shopping Cart