I recently saw a hotly debated post about the question of which power source to use for racing - smart trainer or Assioma Duo. I use a Zwift Hub, but until very recently used my Assioma Duo as the power and cadence source as they are more accurate. Two weeks ago or so I switched to using the Zwift Hub as my power and cadence source and double-record my rides. For LIT workouts, the two are very similar. However, I noticed that for low-cadence workouts (at around 300-400W), the Zwift Hub usually reads 10-20W more than my Assioma Duo. Same for high-intensity intervals at higher cadences.
Here comes my question: I am new to Zwift racing; today I did my third race, the first one using the Zwift Hub as my power source. Again, it showed higher power than my Assioma (both the Hub and Assioma were calibrated before the race). The average W on the Zwift Hub was 314, whereas it was only 304 on my Assioma pedals. I am in cat B, so I guess no one really cares, but today I ended up on the podium for the first time and wondered whether I also would have made it had I used the more accurate Assioma pedals. Whatâs your opinion? What should I use for future races?
You can find the dual-recording data from today (24 Jan 2025) in which I used my Zwift Hub as my power source on my ZwiftPower profile (Jonas Grunau). Feel free to also check out the data from the DBR Zwift race on 8 Jan 2025 in which I used the Assioma pedals as my power source in case someone is interested in the context of sticky watts or something like this.
Can you see the data sets on ZwiftPower? I set visibility to public, but Iâm new to this, so feel free to confirm you can see the data of the two races.
Any âseriousââ or Elite racing would prefer/mandate trainer first - but any of the Elite racing series wouldnât let you race on the hub as there is an approved trainer list knocking about.
The issue in the other thread was also the sticky watts and pedalling styleâŚ
I only saw one dual recorded race.
My inexperienced opinion is that it looks ok.
Both power sources appeared roughly within 2-3 %.
The problem with Assiomaâs is people can use an un natural pedal style that overestimates power.
You donât seem to have done so.
Your trainer seems ok and your pedals seem ok as you are using them
I suggest to use the trainer, dual record and continue wearing a HRM.
I donât see an issue but there are far more experienced and knowledgeable sources on the forums.
First, congratulations on your performance really impressive numbers.
Reading from Zwift Cycling Esports Rules & Regs (not sure anyone cares about rules®s) for Elites your primary device would be the trainer, the secondary power recording device (b sample) would be the pedals.
Back to your Zwift Power dual analysis results, if the Assiomaâs have a zero offset/calibration process have you performed that? Thanks for sharing your data, itâs really good only +4% when sprinting.
I was the person who triggered that heated discussion.
I have since purchased a Kickr v 6 and use that as primary source with the Assioma as secondary (although donât always bother as they generally track the Kickr almost identically).
Problem with the pedals is that if you are really on your limit, desperately trying not to get dropped, youâll likely find yourself veering chaotically between Z6 and Z1 in a world of pain. Then you might trigger sticky watts.
I would avoid this as there are some weirdos going around on a mission to expose sticky watt cheaters and the debate can get unpleasant.
Also, your trainer is giving you better watts than the pedalsâŚjust sayinâ.
I think that this is an exaggeration of what actually happens.
Failing rider tend not to rapidly and freq fluctuate between Z1 and Z6.
They may drop to Z2 and recover.
An E racer on the verge of getting dropped might resort to such an abnormal (and higher energy cost) pedal technique to hold on in a tight spot.
This pedal technique never happens IRL.
I also XC MTB and I am out of the saddle all the time but never start /stop at the frequency or the massive change between Z1&6 that we see in e racing.
I do not feel sticky watts is an accident because you have to work hard to do it.
The powercurvers are pretty good, but it is hard to say one is more accurate than the other.
As for dual recordings, there are some âunusualsâ that are easily spottet. Not much here, but if more it would be suspicious
Your pedal power rises more rapid when time â 0
That could indicate that crank length is set wrong
Your trainer har more 20m power
That could indicate that spindown is manipulated
If both manipulated, the curves would typically cross mid, in your case 1:10 minuttes but the average power on both would still be decent
I am not saying you have, and the variance is small, I am saying it is one of the factors (among others) you can spot it.
ButâŚThere will be differences. There shall be as power is measured in two different ways.
Here is one of my finest looking duals. I never get a total overlap like DC rainmaker and the likes, and I have 3 top shelf trainers and 6 crank based dual sided powermeters
As for what to use?
Use the one you feel for, for most that would be the one with the highest reading
Trainers are usually more trusted as a source as pedals can easily be manipulated
Not quite, itâs certainly what I do when I run out of gear/s (more often on a singlespeed than a geared bike), one last push before starting to coast, then a few pushes again and more coasting etc.
When I see this pattern my initial assumption is that the Assiomaâs have a lower crank length setting than is actual.
Trainer primary is generally the best approach because it reduces the number of ways that people can cheat. Some trainers can be exploited etc but itâs trivial to cheat with assioma.
Is it the pattern of initially reading higher then becoming negative?
I would assume the Assiomas should be higher than the trainer.
Mine is but I think it reads above at all time intervals.
Iâll check.
This was my race today.
My trainer was not as calibrated as I would have liked because I was distracted doing a climb portal and forgot to spin down till in the pen with 2 min to go.
