Weight height suggestion for us all

To sort of get around the changes, why dont all of us racers start listing our weight and height in our zp profile. ( something i have been doing for 2 years )
Not the same i know but …

Or maybe Zwift can rely less on weight and height to calculate speed and rely more on just the power output.

To calculate speed from power the most important factor is weight. It is just physics, a smaller mass require less force (power) to travel uphill at a constant speed.

Calculating speed from power is no trivial equation.


All cyclist know that weight is the most important factor when you want to be competitive.


I agree have some agreed format for it and put it in the bio part .

However …

I believe that Zwift may in fact classify that as “harassment” under there new rules because the issue is someone might see it. The issue is not with you sharing the data , the problem they want to address is someone being able to see it .

I don’t think that is the answer, the point is to remove weight so that people don’t live unhealthy to loose weight.

Not as if the whole cycling industry promote light weight components and all pros race as lean as possible.

Weight is not really all that important when on the flats. All world time record events are done on flat surfaces ( indoor oval etc ) Where i live there are literally no hillls. Everyone here is beefy, ride 54, 55 large chain rings, wide rim aero and frames. Aero oval cranks etc. it was not till i had been racing in zwift for a year that i even learned to stand up in a bike when climbing and sprinting :slight_smile:

And there of course you are rather directly hitting a nail squarely on the head .

To a certain extend this entire debacle has been really about whether . Virtual Racing is a sport or not .

There is already at least one very long and esoteric thread on that . This is of course your thread but I think you risk diluting your ask if you introduce all that here . I thought the simple point was . Should we use our zwiftpower bio to disclose our height and weight ?


Yes that is true and even in Zwift weight does not play a big role on flats. But Zwift is not 100% flat. But rolling resistance has a weight factor.

Being a owner of a Personal Training business i personally deal with 20 to 30 people a day. 90% of them want to lose weight. Funny that they are concerned with people being unhealthy for losing weight, No matter how unhealthy that person might be i bet they are better off then being obese. They should be more concerned with out of shape over weight people having heart attacks while zwifting .
They should also fix their algorithm so that lighter weight does not give the advantage that it does on the flats compared to the outside world. From using insider calculations i surmised that a A rider weighing 25 kg less them B rider gets 2 mph free speed on the flats at 300 watts compared to the outside world ( bikecalculator.com ) i also have easily experienced this.


Do you have the Zwift data to share.

I also think this website is a bit more accurate and transparent in there method. Bicycle Speed (Velocity) And Power Calculator

Agree on both counts. Sadly that is all I can do … (other than post a viewpoint in here ) .

Being overweight is better than being dead. But, of course, plenty of people die from being overweight too. I’d agree than on balance more people die from being obese than from an eating disorder. At least in the UK.

e.g. Deaths from eating disorders and other mental illnesses - Office for National Statistics shows that in 2019, 18 people were registered as dying from an eating disorder, whereas it was 534 with obesity as the underlying cause. (via Obesity as cause of death - Office for National Statistics )


Set every rider to be 70kg and then only adjust 10% up or down depending on their actual weight over 70kg. No one can weigh more than 77kg or less than 63kg.
Makes the power number the driving factor much like in real life except on pure mountain climbs.

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Try explaining that one to a) light riders, who all of a sudden would be carrying 5-10kg extra, and b) heavy and powerful riders, who would now waltz up the Alpe with 10-15kg less.

In real life, heavier riders need more power on the flat because they are generally larger (thus have a higher CdA) and generate more rolling resistance.

Zwift uses basic physics equations to model rider behavior. The only place where they have to diverge from “real life” is in the estimation of CdA from weight and height; increasing weight automatically increases your aero drag, which may or may not happen in real life; and the CdA vs height effect is probably too strong - again, in real life there doesn’t exist a nice cohort of riders identical in all aspects except height to test this against.


O that will be awesome that will give me a 4.6w/kg FTP watch out A+ here I come. :sunglasses: :sunglasses:

Zwift does a good job simulating real world efforts. There is some factors that Zwift can’t control like @Robert_C pointed out.


I am going to challenge on that . Subjectively perhaps we can all decide if what we experience is good or not . Its defiantly not bad , but personally anyway I am finding it difficult to give it a good certificate .

Why would I be saying that .

I find in zwift for exactly the same effort I am getting some quite amazing good speeds , and that happens across the power zoning . I know what I can do in Z2,2,4,5,6 training efforts and it is defiantly not what I get from Zwift … there appears to be a bit of a bias towards “Fun is Fast” . . I am not saying that is making anyone more advantaged or not . But I think they are not truly representing those numbers . From normal Z2 training rides right up to full blown races . So IMO we should all take the “realism” with a bit of a pinch of salt at that level. Not really too much problem than that however as its still an equal playing field … or is it .

Here is where I am really struggling to match Virtual with non Virtual . There are very few races I have experienced where the winners of sprint segment would also win the climb segments and vice versa. Where the same riders would also tend to perform even fairly (not completely) similarly in sprint AND climb races .

In Zwift that is much much more common ( even the norm ) . Winners of races ,segment winners just don’t reflect that expectations if simulation was totally accurate (good) . If you need evidence have a look at ZRL results and you will see this is definitely the case . The winners of the races also are statistically almost always taking all the segment points (wins) too . I just don’t think that sits easily explained as an mark of good in accurate simulation . That s not to say for those who want to suggest examples of differences that its flat lined issue . I am just suggesting is that if this was well simulated this would not be quite so clear and evident.

I agree Zwift is maybe a bit faster than IRL but we also don’t stop and have super equipment in Zwift. the point is fast people IRL is also fast in Zwift and Slow people is also slow in Zwift.

Getting to racing, the problem with racing is it is divided in weight classes, so you wont see a 80kg guy win a A flat race because he is winning B same with a 60kg guy winning C because he is racing in A.
Racing is skewed by the way categories work not by the Zwift dynamics.

So in short I agree Zwift is not 100% IRL but it is good enough. But putting people at the same weight will be 100 time worse.

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We wouldn’t expect Chris Froome to outsprint Mark Cavendish. Nor would we expect Cav to get over Alpe d’Huez ahead of Froome.

If Zwift has “Froomes” winning sprints and “Cavs” winning climbs, it’s clearly not good. As long as the “real world” climber types are winning “their” races, and the sprinters are getting to the end and winning their races, all’s well. :smiley:

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