Zwift Vs weight

(Stephan Martel) #1

I did a test on Zwift for those who think that some can cheat according to their weight … here are the results.

Same cyclist
Alpe du Zwift 12.2 Km
Weight 65 kg … 254 watts … 46 min. 55 sec.
Weight 75 kg … 317 watts … 46 min. 56 sec.
Nothing is arranged, I certify it and the two climbs were realized on different days with the same feelings of difficulties.
In short, make your own conclusion …

(SteveK @Cycleoptic ICC) #2

Isnt that to be expected?

If two riders ride at the same power the heavier will be slower up the hills

If that heavier rider uses more power to stay at the same speed as the lighter rider, they will use more power but arrive at the same time?

I agree a coincidence that you took the same time;) good pacing?

PS I’m 105Kg, weight does make a difference :wink:

(Stephan Martel) #3

Hello, as you mentionned for the same speed two people of different weight will have of course two different powers. however, many mentionned the fact that if a person voluntarily modifies his weight will automatically go up faster … in both cases, both climbs have been so difficult …

(Gerrie Delport) #4

So let me see if I understand: You rode up the alpe de zwift twice once with a weight of 65kg and a second time with a weight of 75kg? Is this correct?


So your legs could produce 315w when the virtual weight in game was set to 75kg, 

but when you changed the weight down to 65kg your legs could not generate more than 254w?

something does not make sense!



(Paul Allen) #5

Yes, one is 3.91 w/kg and the other is 4.22 w/kg, but it can really make a big difference on how you use your watts.

Average watts does not tell the entire story

(Joe Daknis) #6

Agree with Gerrie.  The OP makes no sense.  Or, at the very least, it makes no sense without more context. 

Rider 2 is putting out nearly 25% more power at only ~15% more weight. Translates to 8% more in terms of w/kg.

What is your actual weight, and what trainer are you using? If you are 75 kilos and only rode at an average of 254 W as Rider 1 (the ‘weight doper’), then your avg w/kg was, in reality, 3.4 on that effort. 

There is no way that the difference in perceived exertion was equal between one ride at 3.4 w/kg and another at > 4.2 w/kg on a segment that long.

Something doesn’t add up. 




(Stephan Martel) #7

I’m not saying that this has any or no sense … I’m not trying to make you believe anything. I believe that too many variables counteract the accuracy of the whole. My actual weight is 75 kg … Tacx Bushido Smart in both cases (calibrated before testing) I have been cycling intensively for 25 years and I can confirm that I have not experienced an effort beyond 3% … especially at this level of intensity which represents for me, about 92-95% of my maximum.

Once again make your own conclusion…

(Tomas S) #8

Im sorry i dont get this! are you saying that you gave  92-95% of your max in both those rides?

(Stephan Martel) #9

Could you please let me know why some used the button scores (plus or minus) on post that relates on simple facts …at least, say why please.

You don’t like the subject, pls do not answer.

The point here is to share information that I simply experienced. It is not a matter of saying whether you are in agreement or not, but in doubt why not experience it yourself and share your own results.

I just find the experience very curious, that’s all :slight_smile:







(Nigel Doyle) #10

My conclusion is that if you artificially lower your weight in Zwift then when you climb you don’t have to put out as much power as a heavier rider to maintain the same speed. Same conclusion as what others are getting.

Kudos to any 75kg rider that can average 317 watts up the Alpe du Zwift climb. I’m 77kg and my best effort is 52:20 at an avg 286w (Power meter).

I agree about average power not telling the entire story. My experience is it pays to go really hard on the steeper sections where you have the potential to lose the most time then ride at a lower power on the easier gradients. Almost like an over / under interval workout.

(Gerrie Delport) #11

I just think you were tired on the ride where you changed your weight to 65kg. That is why you were not able to generate the same watts going up. 

I can put out the same watt no matter what the in game weight is. 





(Joe Daknis) #12

"The point here is to share information that I simply experienced. It is not a matter of saying whether you are in agreement or not, but in doubt why not experience it yourself and share your own results.

I just find the experience very curious, that’s all** :-)"**


I think the reason you keep getting ‘down-votes’ is because the premise of your post is unclear.

What you’ve shown with your data are that two riders of different weights will have different average power figures when climbing the same distance at essentially the exact same speed. The lighter rider needs to produce significantly fewer watts than the heavier rider.  This is not a surprise, just a confirmation that the game physics make sense.

Where (I suspect) you lose people is in the way you’ve presented it.

When I read your post, I took it to mean that you found yourself physically unable to produce the same avg power on the climb after you reduced your Zwift weight.  That is, that you rode (somehow) at the *exact same level of exertion* w/ the same trainer resistance and measured only 254 W at 65 kg - even though the same force exerted on the pedals nets you an average of 317 W when your ‘game weight’ is 75 kg.

If this is truly what you meant to say, then it’s hard to wrap one’s head around.

If you, as a 75 kg very fit rider, can put up an avg of 317W on that segment, you ought to be able to do the same w/ a ‘game weight’ of 65 kg - and this would make your avatar climb the Alpe in a much shorter time (assuming you used the same general tactics w/ regard to when and where you’re applying more/less power on both attempts).      

(Stephan Martel) #13

Let s start again … I have a weight of 75 kg in reality. I went up the Alpe , ie indicating on the parameters of Zwift that I have a real weight of 65 kg. So, 10 kg lower than reality…I cheated voluntary. So I left with a sustained effort that represent about 92-95% of what I can sustain over the duration of the climb. I had as a result at the end of 254 watts with a time of 46:45 min.

3 days later, I redo the exercise and using this time my real weight, 75 kg, by providing the same physical effort. that is about 92-95% of my capacity … I have as results: the same rise time but with an indicated power of 317 watts.

In short, I did not climb faster because I changed my weight on the software …
Some people say that by indicating a lower weight, the rise time will be to your advantage … This is not what happened.

Is it clearer …

Note: When I mentionned 92-95% of my capacity, it is not a value indicated somewhere but rather what I can push physically and represents a threshold of pain.
In short, I arrived at the top with equivalent pain and fatigue.

(Nigel Doyle) #14

Stephan - something’s wrong with your power measurement then. The same effort will result in the same / similar power output regardless of what weight you input into Zwift. There is no correlation between weight entered and how much power you can put out. The only difference is that lowering your weight will make you climb quicker as your watts/kg ratio is higher for the same power output.

Personally I wouldn’t trust the power your Taxc trainer is providing. Their wheel on trainers have a reputation for over stating the power.

(Joe Daknis) #15

" This is not what happened."

It’s not what happened because your power output wasn’t equal on both days. 

Two variables were different, not one.

What was your HR on the day you rode at 254 W vs. the day you rode at 317W?

If you want to objectively compare the effect of ‘weight doping’, make it simpler on yourself. 

Try a workout in ERG mode on a rolling course.  Set the wattage to something sustainable.  Say…  200 watts.  Ride with your weight set at 60 kg for 30 min.

Repeat on the same course with the same fixed wattage and duration @ 75 kg. 

Which rider travels further over 30 min? How much further? Compare average speeds. 


Same fixed wattage. Same rider. Two weights (and two sig diff w/kg).  Who goes further in 30 min?





(Stephan Martel) #16

Same HR, same Freshness, same feeling, you can not increase or reduce you max, capacity by far…

By experienced, I’ve made so much hill segments and the difference is always few seconds…

Anyway, it’s what I observed and of course I will repeat it.

(Stephan Martel) #17

NIgel, If my Tack is off, it will be continuously and also from one time to another … the offset value will be reproducible from one time to the next. In short, have you tried it? it might be good to do it.

(Nigel Doyle) #18

Stephan - no I haven’t tried a Tacx wheel on trainer or have any desire to do so. I’m running a power meter and Cycleops Hammer.

You need to be more scientific and consistent in your tests and do as Joe describes. 

(Ivo Ritters) #19

Same HR, same freshness, same feeling, same effort = same average wattage…but it isn’t in your case (254 vs. 317 W) and this is what makes everyone confused.

The average wattage does not depend on your virtual weight. It is only your legs.

I do not understand how you can produce so different wattage in both attempts when putting in the same effort. How do you measure the power (power meter, smart trainer)? Have you updated the firmware of the Bushido?

Weight makes certainly a difference in Zwift. A 65 kg rider creating 300 W (4.6 W/kg) is faster than a 75 kg rider (4 kg/W). The heavier rider has to create 345 W to keep up with the lighter rider.  Even the selection of your virtual bike makes a difference on long climbs. There are already many tests/comparisons made by some users. 


(Stephan Martel) #20

254 and 317 are the values given my Strava when I finished my workout on Zwift…This depending of what I put in the system as a Weight value

The 92-95 % is what I gave to the pedal…the human itself at almost it’s maximum.

If I said to You… give me your maximum for 45 min.(forget the numbers)…this is what I did on both workout, using same HR, same freshness…