Favero Assioma Duo Power Meter Review: The Science of Watts

There’s a familiar deception in cycling. It’s the feeling of a “good day” on the bike, a sensation of flying, where the wind feels like a gentle push and your legs feel limitless. Then, you look down at your computer, and the numbers tell a different, sometimes humbling, story. Conversely, there are days of gritty struggle, battling a headwind, where every pedal stroke feels like a monumental effort, only to find you were holding your best power of the season. In this gap between perception and reality, one metric stands as the ultimate, incorruptible truth: the Watt.

For years, accurately measuring this unit of power was the exclusive domain of professional teams with five-figure budgets. Today, that lab-grade technology has been refined, miniaturized, and made accessible. Our subject for dissection is a prime example of this democratization: the Favero Assioma DUO. While you may see it listed under a reseller’s brand like ‘RiseUP’, make no mistake—the engineering heart beating within these pedals hails from Favero Electronics, an Italian company obsessed with precision. We’re not here to just review it. We’re here to pull it apart, molecule by molecule, to understand the science that transforms your raw physical effort into pure, actionable data.

The Ghost in the Machine: How a Pedal Reads Your Power

At its core, a power meter functions by measuring the tiny, almost imperceptible flex in a metal component as you apply force. The Assioma places this “nervous system” inside the pedal spindle—the steel axle around which the pedal body rotates. This system is built around a series of electronic components called strain gauges. Think of a strain gauge as a microscopic nerve ending for metal. As you push down on the pedal, the spindle flexes by a few micrometers. These gauges, bonded to the spindle, are stretched and compressed along with it, causing their electrical resistance to change. It’s this minuscule change in resistance, amplified and measured with incredible sensitivity, that forms the first half of the power equation: Force.

But power isn’t just force; it’s force multiplied by velocity. This is where things get complicated, and where Favero’s ingenuity begins to shine. A common assumption for older or simpler power meters was that your foot travels in a perfect circle at a more or less constant speed. But anyone who has ever ridden a bike knows this is false. Your pedal stroke has “dead spots” at the top and bottom, and your speed accelerates and decelerates throughout the 360-degree rotation. Relying on an average angular velocity to calculate power is like trying to capture a hummingbird’s flight with a blurry photograph—you get the general idea, but you miss all the critical, instantaneous details. This method can be fooled, especially by things that intentionally alter pedaling speed, like oval chainrings.

To solve this, the Assioma DUO doesn’t just have strain gauges. It has an inner ear. Each pedal contains a three-axis gyroscope. This tiny MEMS (Micro-Electro-Mechanical Systems) chip, the same technology that lets your smartphone know which way is up, constantly tracks the pedal’s exact position and, crucially, its real-time speed at every single point in its rotation.

Unlocking IAV: The Genius of Instantaneous Angular Velocity

This gyroscope is the key that unlocks Favero’s signature technology: IAV Power, or Instantaneous Angular Velocity. Instead of using a flawed average, the Assioma’s internal brain uses the gyroscope’s data to calculate the pedal’s true velocity at the very instant a force measurement is taken from the strain gauge. It performs this calculation hundreds of times per second.

The difference is profound. It’s the leap from a blurry photo to a 4K, high-speed video of your pedal stroke. With IAV, the system doesn’t care if you use oval chainrings that speed up your foot in the power phase. It doesn’t care if your cadence is wildly erratic during a desperate sprint for a town sign. It simply measures the true force and the true velocity at that exact millisecond and calculates the true power. This is the scientific foundation behind Favero’s claim of ±1% accuracy. That number isn’t just a lab-verified peak performance; it’s a promise of consistent, reliable accuracy out on the road, in the messy, imperfect reality of actual cycling.

Forged for Reality: Engineering That Endures

A sensitive instrument is useless if it can’t survive the harsh environment of the road. Favero’s design philosophy clearly prioritizes resilience. The first enemy of consistent electronics is temperature. Metal expands and contracts with heat and cold, which can affect strain gauge readings. The Assioma counters this with Automatic Temperature Compensation (ATC). Between -10°C and 60°C, the system constantly monitors the temperature and adjusts its calculations accordingly, acting like a built-in thermostat for data to ensure your 300-watt effort on a cool morning reads the same as a 300-watt effort under the blazing afternoon sun.

The second enemy is physical assault from water, mud, and impacts. Rather than relying on simple seals or gaskets that can fail over time, Favero protects the Assioma’s entire electronic brain—the strain gauges, gyroscope, and processor—by completely submerging it in a bi-component resin block. The components are placed in a mold, and a liquid resin is poured over them, which then hardens into a solid, waterproof, and shock-resistant amber. This is how the pedals achieve an IP67 waterproof rating, meaning they can be fully submerged in a meter of water for 30 minutes. They are, for all practical purposes, impervious to rain, puddles, and bike washes.

This focus on robust, sealed design informs the choice of an integrated, rechargeable battery. While some may prefer replaceable batteries, a non-removable design eliminates a major point of water ingress—a battery door. The convenience is undeniable. A single charge, delivered via a clever magnetic connector that clicks satisfyingly into place, provides at least 50 hours of ride time. For most riders, that means charging only once or twice a month, a small price for total environmental sealing.

The Power of Two: Why Dual-Sensing Matters

The “DUO” in the product’s name signifies that each pedal is an independent, fully-fledged power meter. This is more than just a premium feature; it’s a powerful diagnostic tool. No human body is perfectly symmetrical. Almost every cyclist produces more power with one leg than the other. The Assioma DUO doesn’t just give you a total wattage number; it shows you the precise Left/Right contribution to that total.

Observing this balance can be revelatory. It can highlight a muscular imbalance that needs to be addressed with strength training, preventing long-term overuse injuries. It can be a key indicator of fatigue, as your dominant leg often takes over more of the work when you’re tired. For riders returning from an injury, it provides objective data on whether the recovering leg is truly back to full strength. The goal is not necessarily to achieve a perfect 50/50 split, but to understand your unique, personal baseline and notice any significant deviations from it. It’s the difference between knowing your car’s total horsepower and having a detailed diagnostic report for each individual cylinder.

A Tool of Understanding

Ultimately, the Favero Assioma DUO is more than just a gadget that spits out a number. It is a finely crafted scientific instrument. It represents a beautiful synthesis of robust physical engineering—from the resin-sealed electronics to the simple installation—and elegant algorithmic problem-solving in the form of its IAV system.

The true value of such a device is not merely in the watts it displays, but in the understanding it fosters. It closes the gap between perception and reality, replacing guesswork with objective fact. By making professional-level data accessible, reliable, and easy to interpret, Favero has created a tool that empowers cyclists to move beyond simply training harder and start training smarter. It is a testament to the idea that the best technology doesn’t just make you stronger; it makes you wiser.