The first power meter patent was filed 40 years ago as SRM’s Ulrich Schoberer kickstarted a revolution in cycling data that has yet to be rivalled.
Watts remain the dominant metric in everything from training drills to sprint-winning surges, and power numbers are the great leveller that shows just how strong you are as a rider – with sections of the internet cooing over (or questioning) Tadej Pogačar’s mind-boggling numbers as the Slovenian powerhouse routinely tears up the w/kg rulebook.
As with all new technology, the first power meters were prohibitively expensive and reserved for the pros or those with deep enough jersey pockets. Despite being around commercially for almost four decades though, they still remain a significant investment for amateurs, unlike more affordable sensors like heart rate monitors and GPS-touting head units.
Italian manufacturer Favero understands this, and has been offering an affordable pedal-based alternative since 2015 without truly catching fire. Its third iteration – the Assioma Pro RS – looks set to change its fortunes though, and those of the cyclists for whom power has always been slightly out of reach.
Pedal power
The Assioma Pro RS power meter pedals look like a standard set of Shimano SPD-SL-style pedals on the surface. And that’s because its carbon fibre-reinforced polymer pedal bodies are just that. It’s the spindle where the magic truly happens.
The pedal’s predecessor – the Assioma – housed the strain gauges in a pod between the pedal body and the crank arm, and is a design seen on other power meter pedals like the Wahoo PowrLink Zero. The updated Assioma Pro RS meanwhile is more in line with the Garmin Rally RS range, locating the strain gauges and rechargeable battery within the steel spindle.
Not only is this more durable than the pod-based design, keeping the electronics out of the firing line from road debris, but it also helps create a greater seal, preventing water ingress into power ports or batteries. Favero claims an IP67 rating – they can be submerged in a meter of water for up to 30 minutes – for the product’s entire life and backs this up with a two-year warranty.
Also like the Garmin Rally RS200, the spindle can be swapped between pedal bodies, allowing you to replace the Shimano SPD-SL-style body that comes with the unit should it get damaged. Or – and this is the really clever part – install a Shimano SPD-style body for cross-country mountain biking or gravel riding. This feature means that, by investing in a pair of the Favero Assioma Pro MX pedal bodies (roughly £100 for the pair), you essentially get a power meter for all occasions.
Finally, you can’t talk about the Favero Assioma Pro RS power meter pedals without honing in on their wallet-friendly price tag. When bought direct from the brand, the RS-2 (the dual-sided version) is £540.83. If you just want a single-sided version (RS-1), it’ll set you back just £332.50. This blows the Garmin Rally (£929.99 dual/£594.99 single-side) and Wahoo Speedplay Power (£679.99 dual/£479.99 single-side) out of the water. You’re not cutting corners to get there either – the Assioma Pro RS a slick and sleek pedal that belies its relative affordability.
Fast start
Installing the Favero Assioma Pro RS is as simple as swapping a set of pedals. After charging them with the supplied USB-C cables and magnetically connecting ports (meaning you don’t have to remove them to recharge) and waking them up with a spin of the cranks, it’s time to dive into the Favero smartphone app to complete the set-up. After five minutes of following the illustrated guide, connecting them to a head unit (where you set the length of your crank arms) and calibrating, they’re ready to go.
It’s important to note that to get the most out of the pedals’ plethora of cycling dynamics data (more of which I’ll go into below) an ANT+ connection is essential – with Bluetooth providing power output and left-right balance only.
The Assioma Pro RS are also only currently available with a Shimano SPD-SL pedal body (meaning, unlike the Garmin Rally, no Look Keo model yet), but the matching cleats are also supplied should you need to make the switch on your shoes.
If you do want to swap pedal bodies to the off-road-leaning MX version, the process is slightly more involved, but nothing beyond the average home mechanic armed with a set of 6mm Allen keys. After removing the external cover on the outside of the spindle housing, there is another nut to undo to free the spindle from the pedal body. You repeat the steps in reverse with the new pedal body and the whole process of switching between bikes and pedal bodies takes less than 10 minutes.
Industry-leading data
A power meter is only as good as its accuracy, and here Favero claims the now-industry standard +/- 1%. In practise, this means that it should be as good as power meters twice its price point, begging the question, why would you pay more?
Before diving into its real-world performance, it’s worth noting Favero’s proprietary IAV Power System. An integrated three-axis gyroscope within the spindle, it adds real-time angular velocity (the rotational speed of the pedal during a stroke) into the power calculations rather than relying on an average. Favero claims that including this helps the Assioma Pro RS to its stated accuracy, with the angular velocity particularly important during climbing (where pedal strokes are irregular) and when using oval chainrings, where the elliptical shape accentuates the variations in angular velocity.
During testing, I put the pedals’ durability to task in varying conditions on winter roads in the UK, and verified their accuracy against the Muov Bike and Wahoo Kickr Bike Pro trainers indoors.
When riding in the real-world, the pedals blended seamlessly into my set-up, adding almost endless fields of data to my head unit and plenty to pour over when returning home. The battery life has stood up to Favero’s claimed 60 hours too – I have ridden with them exclusively for two months, and haven’t had to recharge them yet.
Aside from the big power-based data fields like Normalised Power and TSS, I was interested in diving into the pedalling stats. The pedal power phase and balance data has shown its time to embark on some pedalling drills to improve my efficiency, while Favero’s Platform Center Offset (depicting where force is distributed across the pedal platform) has helped me to refine my cleat position.
When it came to the side-by-side testing, during longer efforts, the Assioma Pro RS pedals essentially mirrored both the Muov Bike and Wahoo Kickr units, which both also claim +/- 1% accuracy. But on efforts of five minutes or less, there were subtle differences, which can be attributed to the Assioma Pro RS’ increased accuracy and real-time angular velocity compared to the smoothed nature of indoor trainers.
Zooming in on the power field for the entire workout, the Assioma Pro RS’s line is like that of a polygraph, waving up and down to track the constantly shifting differences of output with each pedal stroke, compared to the relatively flat line of the Kickr. This translates to higher one-second maximum efforts (944 watts v 929 watts), while slightly more tempered five-minute slogs (317 watts v 323 watts). Although within 2%, I’m inclined to agree with Favero’s version of events.
A power meter revolution
Although pedal choice is often ingrained, if you can look beyond its Shimano SPD-SL pedal body, it’s difficult to find a fault in the Assioma Pro RS. Relatively affordable, easy to install and swap between bikes and disciplines, and with accurate real-time power figures to boot, they outperform their Garmin and Wahoo rivals on price and are a great pick if you like the idea of being able to capture power and pedalling data across multiple bikes.
Even if you only need a power meter for a sole bike, the Assioma Pro RS are cheaper and easier to install than most crank-based systems. Plus, you’re futureproofed if you do ever plump for that n+1.
