4iiii manufactures the PRECISION and PRECISION PRO power meters. The PRECISION power meter (pictured below) is a left-only crank arm-based power meter with models available for both road and MTB. The power meter takes the power that is generated by your left leg and doubles it in order to determine your total power. At $399 for the Shimano 105 5800 version, the PRECISION is most affordable direct force power meter available. In addition, with an added weight of only 9 grams, it is also the lightest power meter on the market.
In addition to being affordable, lightweight and highly accurate, the 4iiii PRECISION measures precise cadence data, have 3D power meter technology capable of measuring tri-axial strain and are compatible with both ANT+ and Bluetooth SMART devices.
The PRECISION is one of easier power meters to install. You simply remove your current left side crank arm using a 5 mm Allen wrench and a Shimano preload cap tool and then install the 4iiii power meter in its place. Installation takes about 5-10 minutes.
The PRECISION pods ads a mere 9 grams to your crank arm – making it the lightest power meter you can buy.
Left/Right Power Measurement
The PRECISION does not provide left/right power measurement since it is measuring left leg power only.
The PRECISION uses one CR2032 battery. We like CR2032 batteries as they are cheap and very easy to find. Note that batteries are provided with the power meter.
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.
Difficulty to Change
Easy. The battery in the left side crank arm is changed by hand in a matter of seconds – no tools necessary.
The PRECISION transmits data via both the ANT+ and Bluetooth SMART wireless protocols. This means they are compatible with any bicycle computer, smart phone or tablet.
The PRECISION is accurate to within +/-1%. This is on par (to slightly better) than the majority of other power meters on the market.
Like most power meters, the PRECISION uses an accelerometer to measure cadence. An accelerometer is an electronic device that is housed inside the power sensor and measures your pedaling rate.
The PRECISION 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.
The PRECISION comes with a one year warranty which covers the product from defects in material and workmanship.
4iiii offers an app for both iOS and Android devices, allowing you to connect your smart phone or tablet to your power meter using Bluetooth. You can use the app to update the firmware on your power meter and to perform pre-ride calibrations (zero-offsets). In addition, the app offers training metrics so you can use it as your primary or secondary head unit.