4iiii Precision Ultegra R8000 Left Power Meter

The 4iiii R8000 Precision powermeter is a lightweight and accurate power meter that will boost your cycling performance. Due to the very lightweight design, the sensor only adds 9 grams to a standard Shimano crank. This makes it the lightest power meter on the market!

Single-Sided Power Meter
The 4iiii R8000 power meter measures the power on the left crank and counts it twice so you get a total power over both legs. For most riders without limitations, the power on the left and right leg is almost the same with equal efforts. Your cadence is also measured as standard.

Battery Life
The 4iiii has no internal battery, but uses button cell batteries. The downside is that you'll need to replace them every now and then. Fortunately, the battery lasts for over 100 hours, which is a lot longer than most internal batteries in power meters.

Connectivity
Calibration is done via 4iiii Device Configuration. This app is available for Android and IOS. Through this app you can also see the status of the CR2032 button cell battery. This power meter sends both an ANT+ and a Bluetooth signal. This makes this power meter compatible with almost all bicycle computers. If you are not sure if your cycling computer or sports watch is compatible, you can check the user manual of your computer to see if it is compatible with ANT+ or Bluetooth and with power measurement.

Technology

• Weight: 9 grams
• Measurement deviation: ±1%
• Power supply: CR2032 (up to 100 hours)
• Power range: 0-4000W
• Cadence range: 30-150RPM
• Connection: ANT+, Bluetooth
• Operating Temperature: 0 to 50°C (32-122°F)
• Storage Temperature: -20 to 50°C (4-122°F)
• Water Resistance Rating IPX7, IPX5
• Pod dimensions (mm): 37.7 x 27.6 x 7.5mm

Compatibility

• This crank arm fits an Ultegra R8000 crankset of course, but also fits other Hollowtech II road cranksets such as: 105 R7000, 105 FC-5800 and Dura-Ace R9100.

Note: The part of the crank on which the power meter is mounted protrudes slightly from the original crank. This can cause problems with some bicycle frames. You can perform a test to determine whether your frame is compatible. To do this, you need to be able to move a AAA battery vertically between your crank arm and the chainstay. As shown on the last product photo of this page. Optionally, 4iiii website also has a handy document that you can print out and stick on your crank. Then you know exactly between which points the AAA battery must be able to pass. If there is enough space for the battery, you can assume that the 4iiii power meter is compatible with your frame!

Delivery includes

• 1x 4iiii Precision Ultegra R8000
• 1x CR2032 button cell battery

Assembly

In order to install this 4iiii power meter on your bike, you must first remove your current left crank arm. Mounting the 4iiii power meter is exactly the same as mounting a Shimano left crank arm.

1. Remove the pedal on the left-hand side.
2. Loosen the two crank bolts at the top of the crank arm and remove the safety pin from the slot.
3. Then remove the crank bolt with this crank tool.
4. Now the crank arm is loose and you can remove it from the axle. You may have to apply a lot of force here. The most important thing is that you do not damage the crank arm.
5. Next, install the powermeter crank arm by following the steps above in reverse order.
6. Then don't forget to fit your pedal to the new crank arm and you are ready to ride!

Frequently asked questions

How do I know if my bike is compatible with this power meter?
Firstly, you need to have a Shimano road bike crankset. If you don't then you won't be able to use this power meter. If you have a Cannondale bike, you also won't be able to use this power meter. Other cranksets which cannot be used are e.g. FSA, SRAM, Praxis and Hollowgram. You can also not use this power meter on Shimano MTB cranksets because of a different design.

You can, however combine this power meter with cranksets of an older generation. As long as the mounting method of the crank arm is the same as the current Hollowtech II crank arms. You may notice a difference in appearance. Below are a number of cranksets that should fit if you meet the space requirements.
FC-5800, FC-6700 & FC-6800, FC-4700, R7000, R8000 & R9000

Furthermore, it is important that you have enough space at the swingarm. If you do not have enough room, this powermeter will not fit. Unfortunately there is no possibility to make it fit. The best way is to check with the 4iiii model.

How do I determine which crank length I need?
Crank length refers to the length of the crank arm and is measured from the centre of the bottom bracket to the centre of the pedal axle. Bicycles are usually delivered with the correct crank arm length for the corresponding body size. In most cases, the length is indicated on the inside of the crank arm. Otherwise, you can measure it yourself. It is important that the crank arm powermeter you purchase has the same length as your current crank arms.

What software and/or hardware is this power meter compatible with?
This power meter sends both an ANT+ and Bluetooth signal. Therefore this power meter is compatible with most current bike computers. However, not all computers are compatible with a power meter. For this, you have to consult the specifications of your bike computer.
The common models of Garmin and Wahoo are in any case almost all connectable. The Garmin Edge Explore cannot be paired with a power meter.
Garmin Edge 130, 520, 530, 820, 830, 1020 &1030
Wahoo ELEMNT and ELEMNT ROAM

If you don't have a cycling computer you can also use the 4iiii app to track your workout power data.

How do I calibrate this power meter?
Calibrating your power meter is very important to measure your power accurately. Make sure there is no weight on the pedals and that your right crank is up and your left crank is down (positioned vertically). Rotate the powermeter a few times so that it turns on. Then you can easily calibrate your powermeter via the 4iiii app. Another possibility is to calibrate your powermeter via your cycling computer. Most bike computers have this option, check the user manual of your bike computer to find out how to do this.