It’s known that being lighter at the same power output lets you go faster both in real life and in zwift. However I’ve noticed that on Zwift being lighter is disproportionality favorable than real-world physics. This was a hunch so I wanted to put some numbers to it. I wish I had the time to do deep…

How did you avoid adjusting CdA for the Zwift figures? Weight (and height) is part of the CdA calculation in Zwift so changing the weight will change the CdA. I assume zwifterbikes accounts for this but I am not familiar with the website. Adjusting weight in Zwift doesn’t impact CDA to my knowled…

Sorry but the initial post doesn’t make any sense. Saying 4w/kg at different weights is the “same power output” is fundamentally wrong for a start. Please read my post carefully. The opening statement is a contextual statement which has nothing to do with what I’m presenting on. Yes, 4wkg at 90k…

That said, I will still stand by the “IRL comparison” being 100% not IRL at all - its just a different theoretical cyclist algorithm from Zwift’s. And doing so with a single assumed Cda for riders of different weight. I agree this isn’t an IRL comparison and its not a perfect analysis for sure. H…

Just note that ZwifterBikes is using the Gribble formula under the hood, so using ZwifterBikes as proof of Zwift with Gribble as proof of Real Life might not be a valid test. That’s a very important point to consider. I hope that someone with the time and know-how may take this idea and perform i…

[image] Thomas: Heavier riders at the same w/kg of course have a benefit, but what I’m suggesting is that benefit is reduced on Zwift compared to real life. But how are you factoring in the pace dynamics 5 adjustments? You will remember light weight riders had a very difficult time with thos…

[image] Thomas: If adjusting weight in Zwift does in fact impact CDA, that’s another conversation to have in my opinion. But I don’t believe this is the case. It does … [image] Have Zwift made it easier for light riders on the flat? In Zwift your CdA is calculated based on your weight and…

Sorry. You’re wrong. That’s the main reason why lighter riders go faster than heavy riders on flat terrain if they are doing the same watts. " While some Zwifters like to say “it’s all about pure watts on flat roads,” it’s not that simple. Weight does affect your speed on the flats in Zwift, since…

But how are you factoring in the pace dynamics 5 adjustments? You will remember light weight riders had a very difficult time with those and being pushed out of groups and then being blocked from moving forward or having to make a big effort to do so. Can you put that in your modelling? Chris, …

Very interesting. If this is true, which coming from a Zwift employee sounds like it is, then I have many thoughts about this. I find a penalty for higher weight into CDA, while in concept makes sense, shouldn’t be applied evenly. But I suppose that’s for another thread.

I see now, weight does in fact play a role into CDA for Zwift. Someone else also linked a useful thread. My main point still stands though, I believe that this weight CDA penalty is contributing to the “slow down” too strongly. For example while in the last 3 years I haven’t grown any (im 25) I hav…

Is Zwift artificially biased in favor of lighter riders?

General Discussion

Dean (.) January 27, 2025, 7:10pm 18

It does …

Topic		Replies	Views
Zwift unfairly favours lighter riders on flat courses (data included) Feedback	54	2565	December 19, 2023
How should Zwift calculate rider speed? General Discussion	85	7458	November 4, 2021
Zwift is not fair to lighter riders General Discussion	41	10499	May 4, 2020
CdA dependency on height issue Racing	57	4968	April 3, 2023
Still waiting on an ultra light rider update Racing	142	5058	January 6, 2023

Is Zwift artificially biased in favor of lighter riders?

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