Chapter 1: PRECISION 3: Introduction and the Goal
Posted by Andrew Davidson on April 5, 2023
Over the past decade, 4iiii has built a reputation as an industry leader in the cycling world, for providing high-quality training tools for riders of all abilities. The PRECISION 3 Powermeter is our latest offering of world-class technology for the weekend warrior to WorldTour pro. A key element upon which the confidence in 4iiii power meters is built is the incredible accuracy our products deliver. Using our patented 3-axis or “3D” strain gauge design we measure the bend, axial and sheer forces that act upon a crank, to provide a detailed account of each cyclist’s unique pedal stroke and power output (see animation below). Alternatively, our competitors typically make use of a single strain gauge and aren’t able to capture the same level of detail and accuracy.
An animation of the instant torque readings of 16 pedal strokes as a rider starts a sprint. Blue is the bend axis, purple is the shear axis, and brown is axial. Note how all three axes change independently and uniquely, as they shift into the sprint. 4iiii 3D strain gauge technology captures all the forces on your crank.
The data captured by our power meters has an accuracy within +/-1%, a claim that users can have faith in, as it’s been successfully validated through third-party testing at the University of Boulder. The analytic work of Dr. Kram on our power meters was exhaustive before 4iiii partnered with the likes of WorldTour teams Quickstep and Bora-Hansgrohe. For further information, A video summary of the research by Dr. Kram and Dr. Copper can be found here and academic papers on it can be found here. As Dr. Kram states, he is surprised that no other power meter companies have taken the opportunity to use his 3rd party independent lab to verify their accuracy claims. We’re surprised too, but we’re proud of the work that our team has done to design and build what Dr. Kram has found to be the world’s most accurate power meters.
What’s the Goal of the PRECISION 3 Powermeter?
The goal of the PRECISION 3 Powermeter is to expand on a technology and history that already has a proven track record, in the form of the PRECISION Powermeter. Rough terrain - think gravel, rumble strips, mountain bike descents has been known to sometimes affect the data being transmitted by power meters. With the PRECISION 3, we set out to make sure we were the smoothest and most accurate in these rough conditions. Below you can see an example of a smoother and more nuanced power reading on rough terrain, versus a “noisy” power meter reading.
Comparative power data from 90 seconds of riding, comparing power from a smooth and “noisy power meter” on the same bike.
We also know riders want a product that’s as low-maintenance as possible, which includes how frequently one has to replace batteries. Based on the data we gathered, we chose a spec of 800 hours of operating (moving) battery life, a substantial increase from the 200-hour life of the previous PRECISION, while still using the same CR2032 coin cell battery. One’s chosen riding conditions will factor into the battery life (eg. if you primarily ride on rough gravel) the longevity may drop to 350 - 400 hours - still significantly longer than any other coin cell or rechargeable power meter on the market.
To top it off, we’ve been able to pack the best accuracy under any conditions and the longest battery life, into a super thin (<5.5mm) and incredibly lightweight (<9 grams plus battery) pod, which opens up compatibility to virtually all bikes on the market. More technology, in less material, has powerful implications for all of our riders!
How did we do it? It’s All About Cadence.
A power meter revolves around its cadence measurement system, both figuratively and literally, as power is simply your torque multiplied by your cadence. In order to produce smooth, responsive power, you need smooth, responsive torque and cadence readings. From a decade of use, we knew that 4iiii’s 3D strain gauge technology produced smooth and well-calibrated torque readings. In order to achieve PRECISION 3’s exceptional battery life, the cadence system needed to minimize its sensor usage yet still produce accurate cadence readings.
A PRECISION 3 1.2’s power output (purple) compared to a competing power meter (navy blue) over a few minutes. The competing product’s power signal sometimes bounces by dozens of watts per sample, while the PRECISION3 1.2’s power measurements are smooth.