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4iiii PRECISION PRO Shimano Ultegra R8000 Dual-Sided Crankset

Josh Matthew July 1, 2022
4.88 out of 5 based on 8 customer ratings
(8 customer reviews)


4iiii’s 3-D tri-axial strain gauge technology, dual-sided power and +/- 1.0% accuracy

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4iiii PRECISION PRO Shimano Ultegra R8000 Dual-Sided Crankset

The 4iiii PRECISION PRO Shimano Ultegra R8000 Dual-Sided Crankset combines 4iiii’s patent pending 3-D tri-axial strain gauge technology with Shimano’s best-selling Ultegra R8000 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 R8000 power meter crankset also 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 R8000 crankset. The power meter is compatible with both ANT+ and Bluetooth SMART devices and is accurate to +/- 1.0%.


4iiii R8000 Dual-Sided Power Meter Options

  • Chainrings: 50/34 | 52/36 | 53/39
  • Crank arm lengths: 165 mm | 170 mm | 172.5 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


Bottom Bracket: This power meter uses a 24 mm Shimano road spindle and must be used with a 24 mm Shimano bottom bracket.

Tip - If you already have a Shimano 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.

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

4iiii PRECISION PRO Shimano Ultegra R8000 Power Meter Specs

Name4iiii PRECISION 2 PRO R8000
Bike TypeRoad
Location of Power MeasurementCrank arm
Left or Both Legs MeasuredBoth
Independent Left/Right MeasurementYes
InstallationMore involved (60 min. estimated)
Crank Arm MaterialAluminum
Communication ProtocolANT+ and Bluetooth SMART
Claimed Accuracy+/- 1.0%
Active Temperature CompensationYes
Weight694 grams (170 mm, 50-34T)
Battery TypeCR2032
Battery Life100 hours
Method of Cadence MeasurementAccelerometer
BCD110 4-bolt asymmetric
Spindle Size24 mm
Q Factor146
Warranty3 years

In the Box

  • 4iiii Dual-Sided Power Meter Crankset
  • 2 CR2032 coin cell batteries
8 reviews for 4iiii PRECISION PRO Shimano Ultegra R8000 Dual-Sided Crankset
  1. Javier (verified owner)

    I have had like 7 power meters from 4iiii and barely any issues (some execptional, but easy to solve). In this case first ride some metrics weren’t available, but playing a bit with the app (that is the weakest point of 4iiii), those metrics suddenly appeared. When it comes to powermetercity, Josh has been very helpful from the start. Highly recommendable.

  2. Stephen Pair (verified owner)

    Was amazed at how easy it was to install and get connected to everything. I love that I can just hop on and get power without calibrating and zeroing out before every ride. Also shipping was surprisingly fast, I got the powermeter before I received the tools to even put it on!

    • Power Meter City

      Great job Stephen! Thanks for taking the time to leave a great review on your new power meter crankset. We are here if there is anything else we can do! Ride safe!

  3. Patrick David

    Amazing customer service. I had ordered a different power meter. It was back ordered 3 weeks. I saw the 4iii was available. The team at Powermeter City quickly adjusted my order and had the powermeter in hand in days. LBS installed the product in 3 mins direct replacement. Downloaded the app and added the device to the app. Calibration is quick. The unit is working as designed, with no issues. Looking to make some gains and PR a few segments I have been trying to break for months.

    • Power Meter City

      Hi Patrick. Thanks for this awesome review! Looks like you are enjoying your new crankset – we hope you will continue to enjoy them and please let us know if there is anything else we can do! Ride Safe!

  4. BOONPENG (verified owner)

    Fast and efficient delivery. The power meter installed and working well with no issue. Would not hesitate to order again from this site if i need another set.

    • Power Meter City

      Hi Robert. Thanks for this awesome review – agreed! These pedals rock! Good luck on your future rides and please let us know if there is anything else we can do!

  5. Florian Neuberger (verified owner)

    4iiii Ultegra Dual Side: Coming from the left side only, the upgrade was totally worth it. The unit simply works, is reliable and accurate (tested with 2 other power-meters and a smart trainer). You even can set your leg imbalance for each site and if the battery dies on one side the measurement of the remaining side will be doubled according to your imbalance and sent to your cycling computer for a smooth ride home.
    It only lags advanced metrics, but that is not an issue for me.

    • Power Meter City

      Hi Florian. We are glad you are enjoying your 4iiii PRECISION PRO Shimano Ultegra R8000 Dual-Sided Crankset. Good luck on your future rides! Let us know if there is anything else we can help you with!

  6. Broc Atkinson (verified owner)

    I am very pleased with my overall experience with not only the product, but powermetercity as a whole. I had lots of questions, which were quickly answered on the website that guided me into purchasing the right power meter for me. Shipping was quick, and product worked just as described.

    • Power Meter City

      Hi Broc. Thanks for this! We are glad you found the right and amazing power meter for you. We hope you continue to enjoy them – good luck on your future rides! Please let us know if there is anything else we can do!

  7. Thomas Airth (verified owner)

    This is a great product have had no issue with them thus far. Been out on a few rides now with them now and they have gone swimmingly. They were sent in a timely manner as well.

    • Power Meter City

      Hi Thomas. Thanks for this kind review. We are happy its working fine and we hope you continue to enjoy them. Please let us know if there is anything else we can do!

  8. Brendan Dolan (verified owner)

    Great meter but…had a known problem setting it up. The battery case on the right side battery contacts needed to be moved to ensure contact with the battery. After I did that, works perfectly. Incredible service from Josh at Power Meter City. Thank you Josh, well done and thanks.

    • Power Meter City

      Hi Brendan, good to hear that! Thank you for leaving a review and for being a great customer. Let us know if there is anything else we can do in the future.

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