Racing Cats need some adjustments Cat A and B

What an energetic thread all of a sudden! After quite a few rather quiet months in here.

I can’t help but feel a bit of Schadenfreude, to quote the Germans, as the flaws of the cat system make themselves known to the division between A and B and all the people affected, some of which were never affected before since they raced in a cat with no power ceiling.

And so you think “now they get it, now they too understand what we have been talking about for years.” But then not all do, still. Or they do in theory but they still just can’t help themselves from reaching for the repair kit.

So, while you guys sulk over some heavy punchy A riders who recently got to race in B and smash the locals, I thought I’d cheer you up a little with a funny picture that I st0led from the interwebz, a meme of sorts:

Have you seen it before? If not, then this is the so-called Tychonic model, an astronomical model by Danish renaissance astronomer Tyco Brahe. It was based on the Ptolemaic model, a far older ancient Greek model, but with some extra bells and whistles (quite a few actually). If that seems too abstract, you could vaguely compare them to the CE model vs the old WKG model, I guess. Just as some point of reference.

Anyway, the Tychonic model was a splendid one, because it had the merit of keeping the Pope happy. Hence old Tyco never had to burn at the stake. The model puts Man, God’s creation, and his home Earth, in the center of the universe, and then everything else revolves around it, the Sun included.

However, Tyco was forced to somehow account for various strange observations made possible by new technology, such as his own telescope, very advanced at the time and certainly not available in the LBS in ancient Greece. E.g. there were observations of Venus moving forwards as usual during the year but then suddenly going backwards for a while. Tyco therefore had to make a lot of changes to the original Greek model, which showed Earth smack in the middle and then the other stellar bodies in concentric circles around it. Among other things, Tyco was forced to offset Earth’s original central position quite a bit, as you can see, or the numbers wouldn’t add up. And then he came up with an ingenious solution to Venus’ and Mercury’s sometimes retrograde movements. They obviously had to… ehum… revolve around the sun… but… but… the sun still revolved around Earth… of course!

The stars were sprinkled on a spherical celestial backdrop that slowly rotated around the whole divine creation. God knows what was behind that backcloth, but some things were just not meant for Man to find out.

I suppose Tyco must have been redesigning and readjusting his model many times as new annoying observations came in and threatened the model. But he kept it together. All in all, it was a pretty (complex) picture.

But then came Copernicus and ruined it all. The damn heretic, may he burn in hell!

Enough history of science.

Guys, just give up. The cat model doesn’t need additional tweaking because it has already reached its highest state. It’s as perfect as it can ever be. All it needs now is just that little cherry on the top: a big cease and desist note. It’s time for Zwift to put Copernicus on the stage and to relegate the power measures of the CE model to the periphery of our solar system, in a pretty concentric circle revolving around the Sun - the Race Results. Why not put that circle somewhere past Uranus?

In the meantime, just accept the fact that racing is borked for now, as it always was. Just live with it and pray for a better tomorrow. Additional tweaking now won’t fix a thing. Power measures were never meant to sit at the center of the universe, that’s just absurd when you think about it.

And no, I don’t care one bit about low attendance in cat A events. Bohoo. There is already another cat that has had low attendance for a long time (once all the cat B sandbaggers were removed) and nobody ever cared. The division between A and B simply doesn’t need fixing, because it’s just a waste of time. Come Copernicus and that and a whole bag of other problems will all fade into distant memory instantly. That’s the only way actually going forward.


Copernicus died before Tycho Brahé was born (just like was thoroughly developed before “racing score” was announced). Otherwise spot on.

Unfortunately given that inverting the zwiftpower scores and re-scaling it from 600 to 1000 took years I don’t think we’re going to get an ELO-type categorization system any time soon.


Correction duly noted. :grin:

We’ll see. I try to keep the faith. They’ve never made promises like these before. And recently they assured us that the work was well underway.

Even more importantly, let’s not forget, they have a bit of pressure now from new competitors popping up here and there. E.g. free-to-play MyWoosh that stole UCI from them the other day. Kind of void of features and riders right now, but the physics is quite alright and the splash screen promises something like “We’re better today than yesterday” and I bet they’re not pulling that one anytime soon. They won’t have to since they seem to have the same funding base as a certain WT team and a certain WT tour by the look of things, all part of the same old deep-pocketed global political and financial PR campaign. And then we have the underdog with a bite, IndieVelo, still in beta, that boasts a distinct racing focus and seems to be going ELO + matchmaking from day one. Now, racing is where the community is at. You’d need to attract users to reach some kind of critical mass, which for the most part is the same as stealing them. But you also need to keep the users…

I’ve told myself out loud (in here of all places) that I’d give them a year to show something substantial, which means late autumn. Then I go bananas again. Or jump ship. Or both. This is just revving a little, keeping the legs warm.

I should’ve raced “A” :grin:

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updated my 1m and 3m power doing the rooftoop kom earlier and my zFTP has gone from 306 to 282

ZwiftPower shows zFTP as 306 (which will get updated on my next race start) where my zwift profile shows 282 so unless there’s something else at play that we don’t know or haven’t been told, 3min does impact the zFTP

Your 5 min. power must have changed as well, or some other PR went out of the 90 day window.
1 and 3 min. power does not impact zFTP.

5vmin has not altered, only updates were 1m and 3m according to the figures showing on my zwift power numbers

Screenshot 2023-08-19 160123
Screenshot 2023-08-19 160334

Bravo for your commitment, but your user base is telling you something different and their experience matches what they are seeing… Then add in, there are actual examples confirming & reinforcing what they are saying…

It’s seems like everyone knows that 3min efforts will drop zFTP other than Zwift HQ.

Talk about painting yourself into the corner with poor comms…

I could show the portion of the code that filters out anything below 5 min., but I guess you wouldn’t believe me as well… :man_shrugging:


Is anyone able to look at Rich’s profile, and explain why his Zwift FTP has gone down, after setting power PBs? What triggered the change?

All I’m saying is that I’m seeing something that you claim can’t happen

… or some other PR went out of the 90 day window.

If I wasn’t sure, I wouldn’t be saying it can’t happen.

EDIT: remember that the power curve used is not only the power records you see on your Zwift profile.

Zwift code has never had hiccup?
You posted not 10mins ago about braking doing something unexpected…

You have direct evidence in front of you, and you double down?

Whilst you may not look at sub 5mins, the effort before 5 mins changes where the curve starts and the steepness of it?

So the numbers given aren’t the only ones that are used? Seems a bit covert

What numbers are you looking at that might not be shown on our feed?

I set a 3 minute PR and my zFTP lowered from 273 to 267. No other records set or expired. zMAP is actually down from the last time I checked it by a couple watts.

i don’t want to contradict david too much because 1: i’m not really all that interested in how it works and 2: i flagged an issue with him through a third party that i believe has been corrected (thanks btw) and i haven’t had a chance to use zwift since so what has been true for me in the past might not be true from now on

but for me at least efforts under 5 minutes have always affected my zftp, i’m 100% certain. i have been training almost entirely in the sub 5 min range for, jesus, maybe three years straight now. my threshold has so long been neglected at this point that my TTE on is 13 minutes

however i want to point out that a sub 5 min maximal effort doesn’t always cause zftp to drop, it can raise it too

edit… greater than 40minute plus durations (expiring or new)? 8min power?

Just a guess. He raced an event on 5/15 which would have expired on about 8/14. It was close to a 30 minute event and was a strong performance. Normalized Power in that event is showing at 304watts which was his highest NP in any event for that duration – close to what his zFTP used to be. But this is all a guess. A number of his profile wattages are based on non-event (ZP listed) efforts, so can’t see whether it could be some other free ride or training activity that timed out of his profile.

I can’t explain why I keep seeing 3 minute efforts affect zFTP over and over again. I don’t have really high confidence in my observations since I don’t know how it works, but I have seen this many times. What I suggest is to take a few examples (start with Rich?) and dig into the data to explain what happened. Maybe you learn something (eg, it doesn’t work the way you expected), maybe we learn something (eg, it’s explained by a change in power at an interval not represented on the profile, or an expiring PR, etc).

Also if the PRs on the profile are not adequate for a user to understand what happened, or expiring PRs are the reason, perhaps those things should be visualized on the profile.


doing a bit of digging on my numbers (90 days previous to yesterdays effort), the 3m effort was updated but was 4w less than it had been but seeing as 3m doesnt make any effect on zFTP it wont be this, 1m 90s 2m all were increased but again don’t affect the zFTP value

the 4m and 5m efforts were set on box hill on June 27th
the 8m through to 40m were all set on the climb portal doing various climbs in July

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