The link for test itself:
This is a quite important issue for those who weights under 70kg and wants to race fair in Zwift.
As a 61kg rider I am okay with being dropped on flats and descends by heavier riders at same wk/g — that makes sense. But on climbs, really?
That’s how it works in reality, which is why that’s how it works on Zwift.
So you are saying that Peter Sagan (or Tony Martin lol) will beat Nairo Quintana on any climb? In Zwift they would, indeed. Please read the test and my post more accurate.
you are assuming they are/can all doing the same watts per kg.
isn’t it something to do with the fact that the power is pointing diagonally so most of the power is still pushing forwards not upwards and gravity is a relatively weak force? So the heavier rider will be pushing more watts so more aiming forwards too. i’m no physicist so i’m more than likely wrong!!
No one ever said that the same w/kg should go at exactly the same speed. It is an easy way to compare to compare effort between different riders. There is a lot more to play on steeper hills the heavy rider will need more watt.
People are to focused on w/kg.
The zwift equation does not use w/kg to calculate speed it uses weight, power , length and all the terrain parameters. Yes watt and kg is in there but not as a w/kg term.
So you can see in the formula above where Power (P) and weight (Frg) is used.
I assume Zwift use a simular equation.
After reading the link you posted, the author is surprised that with w/kg being equal that a heavier rider climbs faster up the Watopia KOM…this seems obvious to me given the fact that a 90kg rider is putting out more absolute power and the flat and downhill sections of that climb will make them faster. Lol. What you fail to include is it is physically harder for a larger rider to match the w/kg of a smaller rider. 90kg clydesdales putting out 6 w/kg sustained up climbs are much rarer then 65kg guys holding 6.
Length and weight are just excuses by the taller and heavier riders. For most of the well trained cyclists there is a clear correlation between length and/or weight and the absolute wattage they can produce, and so in that extend for most riders the watt/kg will be the same depending on their level of fitness and talent.
Im definitely not an expert so take this with a grain of salt and i would love to see some research on this but I think there are diminishing returns on height and weight for absolute power and thus w/kg. What I’m saying is it seems easier for tiny 60kg dudes to fly up hills at 300 watts and 5.0 w/kg than 80kg dudes to put out 400 and 5.0w/kg. According to pro cycling stats the average pro rider is 68.8kg.
I agree there must be some research on this. But also take into account why they are that heavy. Is that because of their length, or just because they are fat or muscular.
You should compare two riders with the same kind of built and same kind of muscle type. And my experience what I see around and my feeling says that length and weight don’t matter that much for well trained cyclists and that it is all about watt/kg.
So yes it is easier for a 60kg dude to put 300watts if he is better trained that a 80kg dude putting 400watts.
Just take a look at the past TdF / Giro / Vuelta winners, most of them are 180+cm. Not that small I would say…
@AlexanderPerdon, If you look at the formulas above you will see that weight does play a role. But there is no term for w/kg.
Riders started using w/kg to compare efforts up climbs, it is not meant to be an accurate estimation on how fast you can climb.
People are to obsessed with w/kg.
@Gerrie Delport
I know that watt/kg is not a complete accurate estimation on how fast you can climb. But given a normal climb of at least 8% you will notice that most of the power is used to overcome gravity. It goes up to allmost 90% of the produced power. To overcome gravity it is all about your weight. So for climbing a real climb at a speed most riders of us will reach, it is more or less about watt/kg.
I am not obsessed with watt/kg. I just respond to this thread because in my opinion there are some false statements that smaller riders have some advantage because of their weight. I think it just all depending on your level of fitness and talent, and most of the time this level of fitness is expressed in watt/kg.
btw. The heavier ride has some clear advantage because the weight of his bike is relative less than for a light rider like me.
Nope. 
Chris Holton gave the simplest explanation. The key is at the SAME w/kg, because that means the heavier rider is putting out more watts.
@AlexanderPerdon: Sorry i did not refer to you as being obsessed with w/kg. I was referring to most Zwifters.
O yes the Post that the OP was referring to is flawed to the point where the climb section that was used contain a lot of flat sections
haha okay, I delved a bit deeper in to that topic and how it works in real life, I have no questions left. But would be great if Zwift had a page with the information about how its physics actually works. Hope for a checkbox for Full Draft at all times, could make regular rides in Zwift much more fun.
Thanks to all who participated in that conversation. I think this thread can be deleted
@Gerrie_Delport
I don’t agree that most Zwifters are obsessed by watt/kg. I guess most of them have no interest at all on this matter.
In case the climb has some flat sections the heavier rider will even have more advantage to the lighter rider at the same watt/kg.
Until there is no clear research on this subject, it is better to stop with statements that smaller / lighter riders do have an advantage in climbing. To people who are heavy I just can say: “Stop eating too much and start training harder, like most of the lighter riders do. To be light doesn’t come by itself, you have to work hard on that”.
@Gleb. Zwift itself does refer to An interactive model-based calculator of cycling power vs. speed
Don’t delete this post, this topic come up at least once a month.
People think heavy riders should be slow because in Zwift we see a person’s weight but not his built.
I used to race at cat 1 level (we called it A but that is not he point) my racing weight was 90kg with 8% body fat. I could not keep up with the small riders on long big climbs but the short ones similar to Watopia KOM or London Box hill I could keep close enough to catch on the down hill.
As @AlexanderPerdon said comments about big or small riders does not correlate to what is easy or not. We all know the weight don’t help you going up a hill that is why bikes get lighter and top racers aim for low body fat. But the fact that you weigh 60kg will not make you fast you need to train and train a lot.
I have something to add here: smaller riders should have smaller frame size therefore lower final weight! #marginalgains
But if seriously, people smaller than 160cm should be able to ride 650c, it is a shame that bike manufacturers rarely make those, check the latest video on GCN by Emma.
Then that change not only can bring a great benefit for female cyclists in Zwift and maybe even might bring attention to that problem in real life as well as will increase the awareness. Most people never heard of 650c road bikes.
I agree with that 
In fact, training hard and losing weight will easily become an obsession and even be an addiction.
During the summer period I was at 3.7 watt/kg @ FTP. At normal weight and normal training I would be at around 3 watt/kg @ FTP. So this obession gives me allmost 25% increase.
@Gleb. I think smaller frame size and/or smaller wheel size will indeed give marginal decrease in weight.
Please can you share what research you did and what answers you found about how heavier riders at the same watts per kg than lighter riders go faster on flats and uphill climbs please and thank you.
Sunday I noticed a 100kg rider at 2.3 going the same speed at Harrogate KOM than me at 2.7 and 63kg, during the slope at 4+%.
