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IAV Power Technology

If you follow us or read any of our articles, you’ll know that we are big fans of Favero’s Assioma Power Meter. The Assioma is Favero’s second pedal. It takes everything that we liked about their previous generation bePRO pedal and makes it better. The bePRO, introduced in 2015, proved to be accurate, reliable and packed a ton of value for the money. The one critique was the installation process was a bit cumbersome as you had to manually set what Favero calls an installation angle. Well, the Assioma fixes that and installs just like a normal pedal. Favero also added Bluetooth SMART and a longer battery life among other improvements. And yes, accuracy and reliability are still there. It’s just a super solid pedal. Well…Favero just raised the bar even higher with the introduction of its IAV Power Technology. What’s that you ask? Let us explain.

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IAV Power Technology

IAV Power Technology (IAV or Instantaneous Angular Velocity), is a firmware update for the Favero Assioma DUO and UNO that became available on May 2, 2018. In short, it makes your Favero Assioma Power Meter more accurate, with Favero citing +/- 1.0% accuracy with the update. The firmware update is available free of charge and can be downloaded through the Favero Assioma App. If you want to stop reading right here while you run to upgrade your pedals, we get it. But for those that want to know a bit of the science behind IAV…here goes.

 

Most PMs Assume Constant Velocity (or Average Angular Velocity)

As we discuss in our article on Power Meters and Oval Chainrings, most power meters make a pretty key assumption regarding your pedaling speed. That is, they assume that your pedaling velocity is constant. That is not to be confused with your cadence. Cadence measures how many times you turn the cranks within a 60 second span. Rather, we’re talking about the speed at which you turn the pedals during each pedal revolution. Again, most power meters assume your speed during each pedal stroke is constant – also called average angular velocity or AAV. Well the truth is, some folks have pedaling styles where their velocity can vary at different points in the pedal stroke. If you’re one of these people and your power meter uses AAV, your power data can be skewed.

Oval chainrings can really cause this problem. Due to the very nature of what oval rings intend to accomplish (speed up your pedal stroke during the dead spot and slow it down during your power phase), they can lead to rather meaningful inconsistencies in your pedal stroke revolution. Most studies say oval rings can skew your power data anywhere from 1.0% to 4.0% (upwards). Favero cites research that concludes errors caused by power meters that use AVV can reach 4.5%.

Favero Assioma IAV Power Graph

 

The Fix: Actual Instantaneous Angular Velocity (IAV Power Technology)

Well IAV Power Technology sets out to fix this issue. Using proprietary software and an integrated three-axis gyroscope, the Assioma can measure actual instantaneous angular velocity. Unlike AAV, IAV takes into account your true pedaling speed within each pedal stroke. It can do this regardless of your unique pedaling style or the shape of your chainrings. But the cool part is, not only does IAV fix the issue of inconsistent pedal stroke revolutions, but in doing so, it also improves the accuracy of the Assioma from +/-2.0% to +/-1.0%. That’s not bad for a free firmware upgrade!

Josh Matthew

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