What they say: Precision pro dual-side power meters deliver all the benefits of our left side model (exceptional accuracy, lightweight design, ANT+ and Bluetooth compatibility, 3D power meter technology), plus a specific breakdown of left and right wattage.
What we say: When we last had a power meter buyer’s guide, back in June 2017, we were impressed with the left-hand crank mounted 4iiii Precision meter and in the time since it’s performed flawlessly giving us high hopes for the dual power Precision Pro version that adds right-hand power to that of the left.
Using the same technology and know-how, strain gauges are mounted on the inside of both cranks, which could have presented a bit of a packaging conundrum on the drive side but it’s been well worked through and actually fits quite cleanly in our humble opinion.
A single CR2032 battery powers each respective side and is said to give upwards of 100 hours use, and rather helpfully gives a warning when either one drops below 15%. It also has another trick up its sleeve in that it’ll switch to one sided power if one of the batteries dies mid-ride, so you don’t lose vital data.
Thinking of which, 4IIII has a reading margin of error within 1% of actual, all for an additional 25g of weight. Currently available in all lengths and chainring options for Shimano Dura Ace 9100, Ultegra R8000 and 105 R7000.
Conclusion: Neat packaging and smart features make the Precision Pro a must have for cost-conscious Shimano users.