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What is the difference between the PRECISION and the PRECISION PRO?

The PRECISION is a left-only crank arm-based power meter and replaces your current left side crank arm. The power meter takes the power that is generated by your left leg and doubles it in order to determine your total power. The PRECISION PRO takes the original single-sided PRECISION to the next level with dual-sided power. The PRECISION PRO locates a power sensor on both the left crank arm as well as the chainring, allowing you to measure both left and right leg power independently.

Can I use the PRECISION PRO on both my road and mountain bikes?

No. The PRECISION PRO is intended for road use only.

How do I know if the PRECISION PRO is compatible with my road bike?

The 4iiii PRECISION PRO comes pre-installed on a Shimano DURA-ACE 9000 series crankset, which uses an integrated Shimano Hollowtech II bottom bracket. Your frame must be compatible with this Shimano crankset.

In addition, the PRECISION PRO needs 10 mm of clearance between the left crank arm and the nearest bike component. This isn’t an issue for most customers, but some frames do have tight clearance so pay particular attention when marking the installation location. Customers with bikes that have bottom-bracket mounted brakes might also have clearance issues. Please see this frame compatibility guide for more information.

How much does the PRECISION PRO weigh?

The PRECISION PRO ads a mere 20 grams to the Shimano DURA-ACE 9000 series crankset. This is almost nothing.

What conditions can I use the PRECISION PRO in?

The PRECISION PRO is waterproof and dustproof, and can be used in temperatures between -20C and 40C. PRECISION PRO power meters can be stored at temperatures of up to 85C.

Can I move my PRECISION PRO from bike to bike?

Yes you can – assuming both bikes are compatible with the PRECISION PRO. However, we note that crank-based power meters aren’t typically moved from bike to bike due to the time it would take to do so.

How durable is the PRECISION PRO?

The PRECISION pod is placed on the crank arm so that it is situated in a protected area. It’s practically impossible to knock it or hit it on the drive side, and while the left side is more open, it is still very well protected. We do not anticipate any issues with durability.

How does the PRECISION PRO communicate with my bicycle computer or head unit?

The PRECISION PRO transmits data via both the ANT+ and Bluetooth SMART wireless protocols. This means it is compatible with any bicycle computer, smart phone or tablet.

How to I update the firmware on my power meter?

Please see here for step by step instructions.

Does the PRECISION PRO come with a warranty?

Yes. The PRECISION PRO comes with a one year warranty which covers the product from defects in material and workmanship.



How hard is the PRECISION PRO to install?

In order to install the power meter, you must remove your current crankset from your bike frame, and replace it with the PRECISION PRO. Assuming you have ensured compatibility with your bike frame, installation is relatively straightforward. You can expect it to take 30-45 minutes, depending on your level of experience.



What type of batteries does the PRECISION PRO use?

The PRECISION PRO uses two CR2032 batteries – one in each sensor. We like CR2032 batteries as they are cheap and very easy to find. Note that batteries are provided with the power meter.

How long do the batteries last? Are they difficult to change?

Battery life is right around the 100-hour mark. When you have 15% battery power remaining, you will receive a low-battery alert on your head unit. This is a nice touch and serves as a reminder to replace your battery soon. The battery in the left side crank arm is changed by hand – no tools necessary. The battery for the sensor that is mounted on the chainring is replaced by unscrewing the three small 1.5 mm bolts that are located on the outside of the sensor cover. (A 1.5 mm hex key is provided with the power meter so you don’t have to worry about sourcing one.) Both batteries can be changed in under five minutes.



Do I need to calibrate (zero-offset) the PRECISION PRO every ride?

The PRECISION PRO should be calibrated before ever ride – which is standard procedure for power meters. Calibration only takes 30 seconds and is performed using your bicycle computer.



I am having trouble updating the firmware on my PRECISION PRO. Any ideas?

Please make sure you have the latest version of the app. For Android devices, it’s version 1.8.0. For iOS devices, it’s version 1.26.0. In addition, here are a few tips to keep in mind when updating your firmware:

  • The closer you are to your power meter, the better (don’t try to update from another room)
  • If you receive a text, email or call on your phone while updating, it can interfere with the update
  • Don’t exit the app until the update is complete

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