Question about Power Scaling (Assioma, 4iii, etc.)

Through the Favero app, you have the ability to do a “Power Scaling” for +/- 15% power output. This means that I could go from doing 400w to 460w with power scaling. This would be a massive issue when it comes to racing and fairness. I know through the 4iii app, you have the ability to do the same thing.

Are there trainers that have this Power Scaling function? Even requiring dual recording isn’t enough to prevent people from cheating this way so long as you find two power meters with power scaling as an option.

If e-racing is to continue growing, and the emphasis on clean racing becomes more important (prize money, sponsorships), Zwift will need to figure out how to mitigate this type of cheating.

TLDR: I don’t see enough people talking about power scaling when it comes to cheating on Zwift.

I didn’t even know this was a thing until now, and I have a single-sided 4iiii crank on my road bike.

As far as I know, no trainers have it as it seems to be for compensating for left/right balance on single-sided power meters, which I assume isn’t a problem for indoor trainers?

most trainers can be tampered with to some extent. it’s trivially easy to tamper with a saris or a direto as long as you’re fine with voiding the warranty

edit: with that said, the zada test probably checks for this kind of stuff. it wouldn’t be hard to figure out if a direto was miscalibrated because the factory calibration number is written on the unit and can be cross referenced in the elite app

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Power scaling is a very useful feature on power meters. It serves a purpose.

What about people with wheel-on trainers? People who don’t zero their meters or who manipulate spindown values? Those who have inaccurate meters?

It’s a can of worms that won’t be solved any time soon.


Sadly power scaling is not detectable outside the native android/ios app as those values aren’t reported back via ANT+/Bluetooth. It is abused by a handful of riders at the A+ level community races including WTRL.

The premier league has self-regulation by teams so not really a problem there.

It’s the main reason Zwift require you to use a turbo trainer as the power source in their events, even if some over-read slightly.

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Yes, many ways to cheat. I just don’t hear about power scaling cheating as much as I do about manipulating spin down values (which seems more complicated. I’ve been Zwifting for many years and still don’t understand how I’d manipulate my trainers spin down values. Conversely, it would take me 5 seconds to cheat with power scaling). This method of cheating is easy, effective, and totally non-detectable.

Another way to think about it. I would need to drop 10kg off my weight to cheat as effectively as increasing my power by 15%. (Actually… not really. If I had a choice between 15% more watts or 10kg less body weight, I’d take the watts every time).

This doesn’t change my enthusiasm for Zwift racing. You’ll still see me on the ZRL start line every week.

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Thanks for responding.

I’m aware that PL requires smart trainers to be ridden. If no smart trainers have the “power scaling” ability, then that’s excellent news for the integrity of the sport.

The point you made about the league being self-regulated by teams resulting in cheating “not being a problem” is, er, problematic. You mean to tell me the individual teams are responsible for ensuring the integrity of their riders and equipment? Hmm.

Self-regulation is far more effective than anything Zwift can enforce as most of these teams have sponsors that would leave if reputation was damaged through cheating.
The real issue is outside this bubble in A+ community races where anything goes.


As James said the self regulation on a whole works okay with the PD, with a lot of teams and riders who do what they can to race fairly and on equal grounds. At PO and im sure on several other teams as well, there are stricter rules for racing in the PD than Zwifts, e.g not allowing the Kickr Core. This does not mean its perfect in any way, as we have seen teams use riders on og hammers, and similar dodgy trainers, also riders with duals matching perfectly in PD races and then having +5% difference in all other races. Then we also throw in the possible conflict of interest between ZADA and Legion being sponsored by zwift last winter together with some other things as well and you sometimes get the feeling that things even in PD aren’t completely fair.

In my perfect world only trainers which do not require user calibration would be allowed at top level racing, but this is not really likely to happen.

If we then talk community its more of a freakshow unfortunately, but there are so many ways to cheat if you want to, that powerscaling/changing slope is just another one to add to the list. Most people still race completely fair, but it only takes one or two cheaters to ruin the race. I mostly race where i know there are requirements for dual recordings or real life data to back up performances, because in my experience you have the smallest change of the cheaters ruining the race in those, and people are willing to flag out people that do cheat as well.

Dual recording etc. are in no way foolproof but right know just the best option for race organizers and riders to enforce some sort of fairness in races. If you want to cheat its very much still possible, and there are at least on guy in the top 20 on the zp rankings, who is doing something to his duals. I dont know if this is just the same powersource on two different units, some sort of powermatch or what, but i have never seen a real dual before where half of the datapoints the trainer are exactly 1 watt higher than the pm


LOL! and again LOL! as a 4 character post is not allowed!