4iiii PRECISION Shimano Ultegra R8000 Power Meter
May 23, 2023$334.99 – $384.99
4iiii’s PRECISION power meter combined with Shimano’s Ultegra R8000 groupset
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.
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.
4iiii PRECISION Shimano Ultegra R8000 Specs
| Name | 4iiii PRECISION Ultegra R8000 |
| Bike Type | Road |
| Location of Power Measurement | Crank Arm |
| Left or Both Legs Measured | Left only |
| Independent Left/Right Measurement | No |
| Installation | Easier |
| 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 | Version 2: 100 hours / Version 3: 800 hours |
| Method of Cadence Measurement | Accelerometer |
| Warranty | 3 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
Common Questions and Answers
Question:Â 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: 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.
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David Morimoto (verified owner) –
I had a very positive experience with Power Meter City. Before making my order, Josh from Power Meter City answered my questions about bike compatibility and tools required for the installation of the 4iiiii power meter. After I submitted my order, PMC shipped the product on the same day. While there was a slight delay in the actual delivery, this was strictly on the UPS side, which I was informed of via the UPS notifications. My power meter arrived in a reasonable timeframe and I was able to install it without too much trouble. I was able to use the power meter data, along with a heart rate monitor, to help me properly pace a climb recently. I’m very happy with my 4iiii Shimano Ultegra R8000 power meter thus far.
Power Meter City –
Glad we could help! Thank you for this kind review, David. It was a pleasure doing business with you! We hope you will continue to enjoy your new power meter and if there is anything else we can do, please let us know!
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!
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!
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!
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!
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!
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!
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!
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!
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!