4iiii XT M8100 Precision 3+ MTB Power Meter

The 4iiii XT M8100 Precision 3+ mtb powermeter is the successor to the XT Precision 3. The Precision 3+ has some new features, including support for the 'Apple Find My' app. This allows you to accurately see the location of the powermeter via the app when you are not using it. So you know where your powermeter is at all times!

New features
Support for 'Apple Find My' allows you to see the location of your powermeter with an Apple smartphone, iPad, Mac or Apple Watch. Simply add the power meter to the app. Furthermore, the new feature 'Automatic Terrain Selector' has been added, which can detect different types of terrain. The powermeter then automatically switches between different methods to measure cadence, accurately measuring your delivered power on any terrain!

Exact measurement
The Precision 3+ powermeter gives a very precise measurement with a deviation of only 1%. Power is measured in the left crank arm and is doubled to measure the total power delivered. For most riders, the difference between the left and right leg is very small, making this powermeter an excellent choice for your bike. When you put power through your pedals or crank, it not only bends the crank, it twists and bends in all 3 dimensions. 4iiii's 3D power measurement system measures this multidimensional load, so you can be confident that your unique pedal stroke will still be accurately measured regardless of your riding conditions.

Connectivity
The 4iiii Precision 3+ power meter transmits a Bluetooth and ANT+ signal. This makes this power meter connectable to almost all modern bike computers such as Garmin, Wahoo, Polar, Mio, Lezyne and Bryton. Calibration is done via 4iiii Device Configuration. This app is available for Android and IOS. Through this app, you can also see the state of the CR2032 button cell battery.

Battery life
The 4iiii does not have an internal battery, but uses button cell batteries. The downside of this is that you do have to replace these from time to time. Fortunately, the battery (CR 2032 button cell) lasts more than 800 hours, which is a lot longer than most internal batteries in power meters. If the battery is below 15% you will get a notification in the 4iiii Device Configuration. So you are always on time with replacing your battery.

• Weight: 9 grams
• Connection: ANT+, Bluetooth
• Measurement deviation: ±1%
• Power supply: CR2032 (up to 800 hours)
• 3-year warranty
• Water resistance rating: IPX7
• Active temperature compensation
• Power range: 0-4000W
• Cadence range: 30-170RPM

• This crank arm naturally fits Shimano XT M8100.

Note: The 4iiii Precision powermeter is slightly wider than a Shimano left crank arm due to the powermeter unit. This may cause problems with some bike frames. To determine if your frame is compatible, you can perform a test. To do this, you need to be able to move an 8 mm Allen key vertically between your crankarm and chainstay. The last product picture on this page has an image to clarify it. Optionally, 4iiii website also has a handy little document you can print out and stick on your crank. So you will know exactly between which points the 8 mm Allen key should be able to move. When there is enough space for the 8 mm hex key, you can assume that the 4iiii powermeter is compatible with your frame!

• 1x 4iiii Precision 3+ XT M8100
• 1x CR2032 button cell battery

To mount this 4iiii powermeter, you must first dismantle your current left crank arm. Fitting the 4iiii powermeter is exactly the same as fitting a Shimano left crank arm.

1. Remove the pedal on the left side.
2. Loosen the two crank bolts at the top of the crank arm and remove the locking pin from the slot.
3. Next, remove the crank nut with this crank wrench.
4. Now the crank arm is basically loose and you can take it off the axle. You may well have to apply considerable force here. The most important thing is not to damage the crank arm.
5. Then fit the powermeter crankarm by following the steps above in reverse order.
6. Next, do not forget to mount your pedal to the new crank arm and you are ready to ride!

How can I determine what 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. Bikes are basically delivered with the correct crank arm length for the corresponding body height. The length is indicated on the inside of your crank arm in most cases. If not, you can measure it yourself. It is important that the crank arm powermeter you buy is the same length as your current crank arms.

With which software and/or hardware is this power meter compatible?
This power meter transmits both an ANT+ and a Bluetooth signal. This makes this power meter compatible with most current bike computers. Only not all bike computers are suitable for use with a power meter. For this, you will have to consult the specifications of your bike computer. In any case, the common models from Garmin and Wahoo can almost all be connected. The Garmin Edge Explore cannot be paired with a power meter.

Should you not have a bike computer right now, you can also use the 4iiii app to keep track of your workout power data.

How do I calibrate this powermeter?
Calibrating your powermeter is very important for accurately measuring your power output. Make sure no weight is applied to the pedals, and that your right crank is up and your left crank is down (positioned vertically). Rotate the powermeter several times to turn it on. Then, via the 4iiii app, you can easily calibrate your powermeter. Another possibility is to calibrate your powermeter via your bike computer. Most bike computers have this option, check the manual of your bike computer how to do this.