Seems like you don’t understand the point.
The Example was exagerated for a simpler understanding.
The problem actually persists on the slightest weight difference.
Seems like you just want to say that I have problems with my race results. But how would you know that?
Plus: Your wife is just using the other end of this “not fair” calculation.
It’s just the point was made a long time ago, and repeated over and over (and over). Speed based only on w/Kg would make racing on zwift worse not better.
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Can you lead me to the threads please? Seems like I didn’t find it.
This is always a fun topic.
We just have to make sure that we keep it constructive and fun. We are not attacking each other by pointing at different opinions it is just opinions and we can all have one or two. .
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The problem with w/kg is that watts doesn’t scale in a linear fashion with weight. So any system using just w/kg is going to, on average, advantage lighter riders.
Take for example a 70kg rider and a 100kg rider both with FTP of 5W/kg. For the 70kg that’s 350W, quite a high number but a number that most top riders are capable of. For the 100kg rider that’s 500W. I’m pretty sure no-one in the pro peloton has an FTP of 500W. Bradley Wiggins’ hour record was estimated at 440W. There might be some people in the high 400’s but you could probably count the number of riders in the real world with an FTP over 500W on the fingers of one hand.
If you were to graph rider weight against average W/kg for all the riders on Zwift I am sure you would find that the average W/kg would go down as the weight went up. That’s because, due to phsyiological reasons, watts and weight do not scale linearly.
On top of that you have power profiles. Again a W/kg system would advantage lighter riders in a sprint or 1 minute effort. Imagine a full 1 minute effort up the leg snapper in Innsbruck. You need about 7W/kg to stay with the front of B up that hill. For me, at 80kg, that’s 560W (ouch) while for a 60kg rider it’s a more achievable 420W. Again you run into the issue of watts and weight not scaling linearly.
Stefan is right about one thing. Why do we separate categories by W/kg when that is not the metric used to determine performance? I’ve said this in the other thread but Zwift knows your height, weight and power and the formula it uses to calculate speed from those 3 parameters. Zwift should be using those parameters to determine category and not simply W/kg. Remember, the only reason we use W/kg is because 5 or 6 years ago someone in the facebook Zwift riders group thought it was a good and simple idea. We should have outgrown W/kg years ago.
Having said that, I still think performance categories are stupid and we should be using a results based system.
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Thanks for that, that’s a good argument.
I’ve just checked Zwiftpower and you’re right, seems like the most humanly raw possible Watts are round about 450 on 20 min’s. That would cat the 100kg riders most likely in the B-Cat. They wouldn’t ride with “the pros” in A.
But their situation with speed on W/kg wouldn’t change up that legsnapper. They would still have to push that 7 W/kg.
I still think speed on W/kg would be more fair.
As an example: I ride ZRL with a team. We have a guy 87kg FTP 4.4. I’m 70kg FTP 4.6. If we ride TTT 350W Effort on the front, he’s cruising on the front and in the draft because he never pushes above FTP. After 30mins I’m hangin in for dear life, while he’s pushing sweetspot. That’s ridiculous. On calculation I should do 250W on position 2 in his draft, 210 in position 4. But that’s rarely the case if you ride single file.
And now think of outside riding: @Gerrie_Delport_ODZ calculated 380W for a heavier rider to hold 35 km/h. Drafting outside behind a heavy rider on 35 km/h I would barely touch the 200W mark even in position 2 in the draft.
Even if Zwift changes to a point based system. The advantage for heavier riders would persist.
I guess what I’m trying to say is:
FTP as a categorization is a good idea, because everyone suffers the same on an FTP Effort. Doesn’t matter if you’re 50kg or 100kg.
I’m just trying to equalize the suffering and maximise the people I could race with.
If Zwift changes to a point based system, you would race agains people of similar capabilitys. Fair enough. But everytime you want to race, you have to hope for enough people in you points range to be online and actually want to race.
If Zwift keeps the W/kg system and makes it more fair, I think more people could ride together.
To be honest, what I wish for is:
I want to jump on a 20 to 40 minute race, whenever I want with at least 25 people in my Cat. And I want it to be a hard Effort for everyone.
There would already be enough people riding Zwift to make this possible. The problem is: lighter riders don’t want to race flat courses. Because we should enter longer races on hills which take over an hour and ride with 5 other guys, cuz no one enters hilly races. And if we enter Crit Citys, we get smashed by Zwifts algorithm which favors heavier riders.
Plus: The fitter you get - and most of the time you loose a few kg on the way - the more you realize this. So you end up on 75 kg with and FTP of 340 Watts and get smashend by heavy B riders. Frustrating.
So you want physical equalization and more hilly races on Zwift?
Good question, thank you.
Yeah, I want physical equalization. I don’t care if hilly or not.
Physical equalization races could be a special kind of race alongside races with W/kg categories and races with result-based categories. The race organizer should be able to decide.
Yep, ultimately true. 
A switch to w/kg would not make it “more fair” - it would likely merely disadvantage those who are heavier (again noting that light riders are NOT disadvantaged at all in the game). The mechanics of the game, which is based on real-world science by the way, dictate that for flat courses ultimate power (W) and not specific power (W/kg) are the significant contributory factor to speed (aerodynamics also obviously come into it but weight is increasingly immaterial the flatter the terrain). A 75kg rider with an FTP of 300W is in no way disadvantaged compared to a 100kg rider with an FTP of 300W (i.e. being light weight is not penalized - its actually quite the opposed when it comes to going up a hill, but this is the same in IRL so that’s fine, and you don’t see all the heavy chaps moaning about how difficult it is to do a sub-1hr alp ascent).
By your suggestion, a 50kg rider putting out 100W (i.e. 2W/kg) and a 100kg rider putting out 200W (i.e. 2W/kg) should go the same speed in game, when plainly this in no way reflects reality.
If the concern is the ability to achieve a competitive categorization system for races, that’s one thing that I believe most would support, but calling for the entire mechanics of the game (which intend to model IRL physics) to be dropped, that just doesn’t make sense…
Partly true Andrew. While you’re right, that it’s good to recreate real life situation and that pure watts matter more on the flat it’s still not as riding outside at the moment.
Drafting simply doesn’t work as outside! It feels harder in Zwift. And based on a TTT Article on Zwiftinsider this seems to be true. The Author there did run tests and createt a TTT calculation sheet, basically saying: First rider in the draft saves 23%, 2nd 30% and after that everyone saves 34%.
IF Zwift is really calculating just percentages off of pure Watts for drafting, then having more pure Watts undoubtetly puts you in an advantage. UNDOUBTETLY!
Since no one of us can say for sure how they calculate Draft and Speed we just have to backward engineer this with this tests, which are - at the moment - proving my point.
Example Cat C 3,0 Wkg:
Rider A 80 kg - FTP 240W, Rider B 120 kg - FTP 360W.
Rider B is at the front of the pack doing 360W. Which power must Rider A produce? Yehh, right: 277W!!!
Rider A gets categorized on FTP and just to hold the wheel of another rider he has to go over his thrsehold.
THAT’S BASED ON ACTUAL TESTS!!!
Tell me that’s fair.
@Andrew_Jones6 how long do you think Rider A could hold the wheel of rider B outside on a flat course?
And please stop assuming I just want to shift the system into my favor. I WILL NOT PROFIT THAT MUCH FROM THAT CHANGE. Since I’m already riding A-Cat, where weight differences aren’t that wide anymore. Nevertheless, the actual fact, that even 1kg weight difference favors heavier riders in the actual algorithm is disheartening.
But to make it even more simple:
@Andrew_Jones6 Do you think, steering, braking, drafting, positioning in the pack, position on the bike and rendering avatars in actual size, weight and body composition is a thing Zwift is able to 100% reproduce in the game?
Do you think, Zwift is able to produce a product which can actually measure how aerodynamic you’re sitting on you’re trainer in the garage?
Because that’s what it takes to produce a system that’s translatable to outside riding.
Let me answer: Yes, that will be possible. BUT SURELY NOT IN THE NEXT 10 YEARS.
So @Andrew_Jones6 : What’s your solution for NOW?
Are the drafting mechanics perfect…no, and from what I understand that there are continued efforts to improve them.
Regarding the manner in which Zwift calculates the drag coefficient of a particular rider, there are limits to the level of granularity that can realistically be incorporated (weight and height don’t appear to be an unreasonable set of inputs upon which to estimate drag).
Regarding the group dynamics [i.e. cornering and positioning within the pack], this is largely irrelevant provided that everyone is subject to the same automated logic - which I believe is the case).
Just because something isn’t perfect doesn’t mean it should be discarded…could it be more accurate (relative to IRL), yes (and, as mentioned above, there are ongoing efforts to improve), but your proposed solution, which is in no way linked to any real world situation and further deviates from real world performance, is IMHO, rubbish.
Lets get the categorization right in order to facilitate competitive racing for all (short, tall, fat, thing, heavy, light, strong, weak) and leave Zwift to continually improve the mechanics of the game.
Now it’s an opinion game.
I think: Inside riding is NOT outside riding and should therefore not be treated as such. It’s a game and I just want it to be fair, no matter how Zwift achives this. On this point of view it doesn’t matter how realistic Zwift compares to outside.
As you said it yourself:
If this would be true, than I’m okay with it. But the tests on Zwiftinsider showed it isn’t. Since the drafting effect favors heavier riders. We are in fact NOT treated equally in the game. 
As per my previous comment the drafting IS NOT perfect, and I don’t think anyone would argue against calls for the mechanics (i.e. how the physics is modelled) to be further improved. The same goes for the group dynamics (i.e. how riders move and position themselves within a group and relative to the road).
But what you are proposing is not the solution…its a BIG step backwards.
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See, that’s an opinion.
And as I stated earlier, I don’t care HOW they do it, but this solution COULD work. Because they would have lesser problems to deal with like height, body composition. aero dynamics, rolling resitance, positioning in the pack, position on the bike and so on. I admit this solution would potentially bring other problems. But under the circumstance that ZWIFT likely never achieves a 100% outdoor copy, this solution is from an economical standpoint pretty smart, since half of the setup is already in game.
And as an example for you:
Say you train on Zwift for an outdoor TT on the exact same course. You will never produce your Zwift result. It’s enough just to coast trough one 180° corner in real life and you’re screwed.
So ultimately Zwift is a training tool for outdoor and indoor racing is something completely different and will NEVER be comparable to outside racing.
According to this blog post, Zwift physics is an idealized version of outdoor riding.
The Physics of Zwift Cycling
TLDR;
Is Zwift Realistic?
The equation of motion looks reasonable from the analysis. Its possible Zwift uses a more complex set of equations as the data I have used is not detailed enough for me to be completely sure on the equation I suspect is being used.
Speeds in Zwift are what you could do in real life in an idealised way, assuming you enter a height and weight into Zwift consistent with what you wear and carry on your real life rides, and ride in a highly trained, pro-like “aero” manner as you would if you were attempting a 1 hour record! Also, it would assume flawless equipment, correctly inflated tires, well-maintained drive-chain, etc. etc.