Using a power meter for training and racing is very valuable. It is one of the first things I would recommend people buying when starting with triathlon after the must-haves, like goggles, wetsuit, bike, running shoes and trisuit. My experience with power meters goes back a few years. I first got a wheelset with a Powertap hub back in 2010, before I got a Quarq crank power meter in 2012, which I had a few of before getting my current Look Keo Power pedals as a Polar ambassador. They have been working great, until the last races where I felt that they where unreliable. And if it is one thing that is important regarding power meters it is reliability. I must trust that the numbers they give are correct. For that reason I started the search for a new solution. Since I use multiple bikes and experience with different crank lengths the pedal based watt pedals were my first choice. What I considered was the Garmin Vector 3, Powertap P1 and the Assioma Duo. Both Garmin and Assioma Duo looked satisfying regarding my criteria, so I opted for the least expensive of the two. I bought mine thru the Norwegian supplier www.wattbutikken.no which offered excellent service.
Pedal-based power meters have been not as good as they should be, until now. All the three mentioned are supposed to be super easy plug and play, which the earlier pedal power meters were not. That’s why I was really excited to check out if they actually could be that easy.
Mounting the Assioma on my TTE was as easy as mounting normal pedals. No need for a special torque, or a unit to put on the inside of the pedal arm (which was an issue with the clearance on the left side with the Look Keo on my TTE). Just mount them and your good to go. Except one thing, they did not pair with my Polar V800, or any of my other units. Damn! Then I had to go back to the source of knowledge, which in most technical issues is DC Rainmakers In-Depth Review. The pedals had to be activated thru Assioma’s own app, before being able to use. On that app, you can check the battery status and adjust the crank length, which is the only information you have to provide and change if you change the bike/crank etc. The change of crank length can also be done from your watch, at least from my Polar V800.
After that, you are good to go. The pedals actually give you the power without any hassle, connection issues or the need for calibration. There is an option to calibrate the sensors from your watch before each ride, or after the warm-up to adjust for the different temperatures. It is recommended, but I have not noticed any difference before and after compared to my Tacx Neo.
On the Assioma app have to activate the pedals. You can also check battery status for the rechargeable batteries and adjust crank length.
For the short time I had it, and roughly 25-30 rides I have been using it seems reliable and consistent. The only issue is that it is reliable and consistently showing a lower number than my Tacx Neo, and the difference is considerable. On 170-ish watts, it is about 10w, 250-ish roughly 15w and from 300w and above it is 20w lower than my Tacx Neo.
I will am not saying that the Assioma Duo shows too low numbers because I do not know who of them are correct, if any. I tried them on another Tacx Neo on my workplace and the difference was identical. The Tacx Neo is not possible to calibrate and is supposed to be +- 1 % accurate, while the Assioma pedals are supposed to be +-2 % accurate. With a 6-7 % deviation between the Assioma and Tacx Neo one (or both) are incorrect. I would love to borrow another pair of Assioma pedals to check, and maybe a pair of Garmin Vector 3 as well, so I can compare. I have access to a Lode ergobike, which they use in scientific projects, and will compare it against that when I find the time. While consistency by far is the most important feature in a power meter I do not think that is good enough. 1 watt is 1 joule/sec. No more and no less, no matter where in the world you are. I know however that some power meters producers are known to give a higher reading than others. In some ways, I understand why, because it is more fun to use a power meter that consistently gives higher number. It makes you believe that you are close to being world class, but a race will tell you the truth. That is also the reason why I prefer the truth from the start.
Using the DC Rainmaker Analyzer, I have compared the different readings in watt from the Assioma pedals and Tacx Neo. The full comparison can be read below. Note that the Tacx app stops the recording when I stop pedalling so that can make the recordings synchronized.
While the uncertainties regarding the difference in values are annoying (which «fault» cannot be put on the pedals without more testing), I must say the pedals really are how power pedals should be. As easy to use as normal pedals, reliable regarding both power consistency and transmitting/pairing. The price is also not crazy expensive costing half of a high-end carbon wheelset. This cost/value aspect is why I would recommend a pedal based power meter high your wishlist if you don’t have a power meter already. I opted for the Duo version which measures both legs. It’s not a must-have, but increases accuracy (since you most likely are stronger in one leg than the other) and will make it easy to spot if one of the sensors are off, which again increases confidence in the numbers 🙂