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4iiii PRECISION Shimano Ultegra R8000 Power Meter

Josh Matthew September 19, 2022
4.94 out of 5 based on 31 customer ratings
(31 customer reviews)

$334.99$384.99

4iiii’s PRECISION power meter combined with Shimano’s Ultegra R8000 groupset

Clear selection

4iiii PRECISION Shimano Ultegra R8000 Power Meter

Introducing the all new 4iiii PRECISION Shimano Ultegra R8000 Power Meter. 4iiii has combined their patent pending 3-D tri-axial strain gauge technology, measured at +/- 1.0% accuracy, with Shimano’s best of breed Ultegra R8000 groupset. The result is one of the lightest, most affordable and most accurate direct force power meters available.

The PRECISION determines your total power based on the force that is generated by your left leg. This left-only design allows for a power meter that is lightweight and easy to install. Specifically, 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:

This power meter is compatible with Shimano R8000 cranksets. It can also be installed on other Shimano road cranksets, as long as they use Shimano’s Hollowtech II interface. 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 R8000 PRECISION 3!

The all new 4iiii R8000 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.

Key Features:

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 work with most Shimano cranksets, 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 versions usually cost more however).

 

Options For This Power Meter

  • Versions: PRECISION 2 | PRECISION 3 (see above for PRECISION 3 differences)
  • Crank arm lengths: 165 mm | 170 mm | 172.5 mm | 175 mm

 

Other Versions to Consider

Dual-Sided R8000 Crankset: We also sell the 4iiii PRECISION PRO Shimano Ultegra R8000 Dual-Sided Crankset which is a complete crankset. It is more expensive, however it measures power from both legs.

Compatibility

Crankset: This 4iiii power meter is compatible with Shimano R8000 cranksets.

Please note, the power meter can also be installed other Shimano road cranksets, as long as they use Shimano's Hollowtech II interface. These cranksets can easily be identified by the two opposing pinch bolts that are used to secure the left side crank arm. Please see the image below and contact us if you have any questions on compatibility.Shimano Hollowtech II Left Crank Arm

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.

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

4iiii PRECISION Shimano Ultegra R8000 Specs

Name4iiii PRECISION Ultegra R8000
Bike TypeRoad
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 (added weight)
Battery TypeCR2032 coin cell
Battery LifeVersion 2: 100 hours / Version 3: 800 hours
Method of Cadence MeasurementAccelerometer
Warranty3 years

In the Box

  • 4iiii PRECISION Shimano Ultegra R8000 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
31 reviews for 4iiii PRECISION Shimano Ultegra R8000 Power Meter
  1. Mike Marsh (verified owner)

    I am very happy with the 4iii Precision 3 from PMC. Josh was very knowledgeable, friendly, and helpful. He even responded to my e-mails after regular business hours. PMC is one of those businesses (and there aren’t many) that I am glad to be a customer of. The 4iii was easy to install, wakes up and calibrates every time. It’s just right for me. Thank you Josh and PMC.

    • Power Meter City

      Hi Mike! It was a pleasure doing business with you too! Your crankset looks awesome! Thank you for this kind review. If there is anything else we can do to help, please let us know!

  2. Luke (verified owner)

    Great price… The Precision is pretty good. My gravel bike uses a Stages Gen 3. Between the two, I feel that the 4iiii is quicker to wake up when I start my Garmin computer… Usually within a few seconds. The Stages will often take a minute or 2. I often will need to search it out to calibrate. They bother calibrate the same way and I don’t think the performance is any different. I think the 4iiii is a little taller and may cause clearance issues near your frame. I haven’t had it long enough to know about battery life, but the new version is supposedly vastly longer. I do prefer the Stages app to the 4iiii one – the 4iiii is pretty bad. I admit that I got the 4iiii because the Stages was out of stock everywhere in my 170mm crank size. However, I am very satisfied with the 4iiii and Powermetercity’s service and awesome price.

    • Power Meter City

      Thank you Luke, Glad you are happy with your purchase! We hope you will continue to enjoy them and we are here if there is anything else we can do! Ride safe!

  3. Rodrigo Muñiz (verified owner)

    Excellent, I installed it on my CH2 Tere without any problem. It synchronises very well with my garmin edge 530.
    I have doubts about the battery door, I am a little nervous that it can open mid-ride, hopefully not.

    • Power Meter City

      Hi Rodrigo, Thank you for this kind review on your new 4iiii PRECISION Shimano Ultegra R8000 Power Meter – we hope you will continue to enjoy them. Good luck on your rides and please let us know if there is anything else we can do!

  4. Jim Brewer (verified owner)

    Thanks PMC for the prompt handling and shipping of my 4iii power meter. I was using a heart rate monitor, but with the power meter I find myself not only enjoying looking at all of the data during and post ride, but pushing harder because I can now see what is actually occurring. The zero offset is simple as is setup. Thanks again, Jim

    • Power Meter City

      Glad we helped you find a solution Jim and thank you for taking your time to leave us an awesome review! We are here if there is anything else we can do! Ride safe!

  5. Carlos Silva (verified owner)

    Very happy with my 4iiii, so far so good, the customer service from PMC has no rival they were able to accommodate all of my requests. Thank you guys once again!

    • Power Meter City

      Thank you for this Carlos – we also want to thank you for being a great customer! We hope you will enjoy your new power meter! Let us know if there is anything else we can do! Ride safe!

  6. Stacker (verified owner)

    PMC is as great outfit to work with. Packing, shipping and support all exceed expectations. I now have two 4iiii left side crank arms. Both have significant miles in all conditions. Both perform excellent and I have no concerns/complaints with my purchase.

    • Power Meter City

      Thanks for this Stacker – we really appreciate it! We are glad you liked your new 4iiii PRECISION Shimano Ultegra R8000 Power Meter. If there is anything else we can do, please let us know! Ride safe!

  7. Sean (verified owner)

    This is a game changer. Having the power information while riding helps immensely with managing training load and conserving energy on longer rides. Installation was easy and just took about five minutes. (Be sure you have a torque wrench.) Power Meter City provided a great level of service, which I found about perfect for an internet merchant.

    • Power Meter City

      Thanks for this awesome review Sean – We hope you will enjoy your new power meter! Please let us know if there is anything else we can do to help. Ride safe!

  8. Tony (verified owner)

    I was concerned I would not receive the latest 4iiii power meter. I sent an email and Josh responded promptly. He assured me that I would receive only the latest device, which really put my mind at ease and an end to my search. My 4iiii power meter arrived quickly and with a follow up from Power Meter City about any concerns of which they were none. THANK YOU SO MUCH PMC!

    • Power Meter City

      Thanks for this kind review Tony. We are glad you finally have your new power meter – we hope you will enjoy them. Please let us know if there is anything else we can do!

  9. Tom S (verified owner)

    The 4iiii template indicated the PM might be a close fit to the chain stay but all went well with several mm to spare. Installation was a snap and the PM paired immediately to both the 4iiii android app and the Garmin head unit. Now I have power on both my smart trainer bike and my outside ride. Sweet.

    • Power Meter City

      Great! Thanks for letting us know Tom. We hope you will continue to enjoy new power meter! Let us know if there is anything else we can do! Ride safe!

  10. Jeramie Thompson (verified owner)

    After researching several different options, I decided to go with the 4iii and couldn’t be more happier and impressed with this power meter. The package shipped quickly and arrived unharmed. The crank was an easy install and paired with my Garmin 520 perfectly. Been on several rides with it and I’m impressed with how easy it is to use and works with my computer. Thanks Power Meter City!

    • Power Meter City

      Looks like you are enjoying them – good luck on your rides Jeramie. Please let us know if there is anything else we can do! Ride safe!

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