Zwift Vs weight

(Nigel ) #21

You’re not getting it. A 45 minute effort at 250 watts is easier than a 45 minute effort at 300 watts. Now your perceived exertion could be similar for a number of reasons e.g. fatigue.

Could also be that your trainer calibration was different on the 2 days.

I’m out of here. We’re banging our heads against a brick wall.


(Stephan Martel ZHR(F)) #22


In short, if you think to voluntarily reduce your weight on Zwift (cheating)to arrive faster at the top, think again it will not be the case...This is what I have tried.

(Paul) #23


Your assumption is incorrect. Dropping your weight within Zwift has no bearing on how many watts you put out. If you would have done that test with also capturing the data on another app or device you would have seen the same watts. Zwift doesn’t manipulate watts in away, this is a fact.

If you don’t know this yet, Zwift speed is determined by the following: Your watts, your ingame weight, ingame drafting, ingame bike used, and virtual elevation changes. 


(Stephan Martel ZHR(F)) #24


Paul, Have you compared the theory that you mentionned with practice? If so, can you share it?

(Paul) #25

What theory, it’s a fact that Zwift doesn’t manipulate watts. It’s also a know fact how ingame speed is determined.

Get yourself a power meter and/or direct drive trainer and try you experiment again, wheell on trainers are know to be off on watts and less reliable then power meters and direct drive trainers.


(Stephan Martel ZHR(F)) #26

Thks Paul


(Stuart Thomson) #27

This thread is hilarious.


(Stephan Martel ZHR(F)) #28

happy to see that it amuses you…we have some fun too !


(Matt) #29

How do we KNOW if zwift doesn’t manipulate our watts…
Deep state is even getting into my darn training…


(Stephan Martel ZHR(F)) #30

Finally, Tour of Watopia, 7 stages, 8 hours 8 minutes…it’s finish not so bad !



(Andre Hufschmid) #31

I have no idea what you wanted to show with your calculation above but if you’re saying you can’t cheat with weight than i think you need to go over your books again.

Let me explain this in a very simple way:

Rider X really weighs: 75KG

He rides Alpe du Zwift at 320W = 320W / 75KG = 4.26W/KG

Now since Rider X is a cheat he lowers his Zwift Body Weight to 65KG. Lowering his body weight in Zwift does not impact the power hes able to produce in real life but it has an impact on the Speed on Zwift…so again:

He rides Alpe du Zwift at 320W = 320W / 65KG = 4.92W/KG

Since hes lighter as a cheat and can produce more W/KG he will climb Alpe du Zwift much faster than real weight Rider X.


(Stephan Martel ZHR(F)) #32

It’s maybe a simple way but it’s exactly not what’s happened in action. If you have read correctly, you will noticed that your calculation do not represent the reality on the bike by using Zwift…

This is what I’m trying to explain…it’s also a simple way to explain it






(Andre Hufschmid) #33

How does Zwift want to know what your weight is? It has no possibility to actually get your weight without you telling it how much you weigh. So why would Zwift presume you are a certain weight and recalculate your theoretic power at that weight? It does not know if you weigh 75Kg, 65Kg or 50Kg if you don’t tell it.

If you’re using a smart trainer, the trainer actually sends the watts your producing to Zwift. The in Zwift Body Weight has no impact on the power you’re able to produce.


(Stephan Martel ZHR(F)) #34

By changing it manually on your profile…then, just making the same workout and compare your results.


(Andrew) #35


I apologise for asking this question, but … when you changed your weight did you do this in Zwift or Strava?

Did you take note of the power on the Zwift screen when you were doing the climbs, or did you just use Strava afterwards?

Can you give links to the Strava workouts?


(Stephan Martel ZHR(F)) #36

I do it On Zwift…I see the change during the workout. The power is lower for the same segment and I take note of the results afterwards on Strava…As I said, for the same heart rate and the same effort I have a lower power but the same time result ???


(Andrew) #37

As others have said, if the two activities were at the same perceived effort and heart rate then the actual power you produced would have been very similar for both rides. Your second ride reported 25% more power than the first - this is massive.

Your trainer should be much more repeatable than this and it can’t just be down to you having a bad day either. It also seems rather unlikely that the difference in power would exactly cancel out the effect of the difference in weight which is why I wondered if you hadn’t actually changed your Zwift weight.

What power do you normally see on other rides?

How about repeating the same segment a few times on the same ride, but with different weights each time? Then there can be no difference in trainer calibration.


(Stephan Martel ZHR(F)) #38

Our last discussions are interesting, contructive and courteous. these are pleasant exchanges…Thks Andrew.

As you’ve said the trainer is maybe off but repeatable and it’s impossible on two fresh days to have a such big difference. The power was about 90-92 % of my maximum and I know me enough to say that both rides were similar in term of effort. Effectectively, I will try to repeat the experience but it’s seems that it doesn’t react as it should be…not in term of power but the way the software respond to the weight variation…


(Paul) #39


If you have another app or device capturing your watts from your trainer at the same time as you are using Zwift you will see they are they same no matter what your weight is on Zwift. Unless you are putting out the EXACT same watts through both rides (no variation at all) you can climb faster depending at lower average watts depending on how the watts are used . 

Again, not sure what you are trying to prove or suggest, but Zwift does not manipulate watts in any way. 

If you want to really test it out get a direct drive trainer or a power meter.


(Stephan Martel ZHR(F)) #40

Paul, who said that Zwift manipulate watts ? For a particular weight, you have associated power…The only thing is that you will arrive to the top at the same time, in my case it’s independant To the weight that I put on Zwift.