Category Enforcement - How is my category calculated? [February 2022]

Unfortunately weight doping will always work. Either it puts you in a lower category where w/Kg is a factor, or it makes races easier than they should be.

Weight is the one issue in Zwift without a clear get-out at community level unfortunately.

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Get rid of weight for racing – make everyone 72kg. Sure it won’t emulate real life, but it will be that much easier to create competitive pens.

It is certainly possible though. Early on in the CE days, I was mostly only doing TTs for races so I had lots of 20+ all out efforts but nothing really in the shorter durations that were max efforts. At some point, one of those TT’s bumped me into A. During the following weekend, I participated in the madness that was @JamesBailey 's Omnium which pushed me to do some short duration efforts and the following week I was back to do to B (where I still am).

I corrected your typos for you


silly auto-correct on my part

Kind of…
If someone does Vo2 intervals or shorter intervals (it doesn’t have to be intervals) fresh during a free ride this is accounted for within CE, it is then presumed this effort can be replicated at any point during a race environment - it’s a different effort to replicate numbers fatigued during a race then when fresh…

CE is better than 95% of 3x20min effort, but let’s not paper over the cracks and pretend it doesn’t have glaring holes…

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I agree with your reasons why someone might add or remove weight. Based on those two reasons (and I know others have written about why they sometimes add or remove weight in non race situations) I’d like to put forward an option which I have, in a round about way, asked on another thread.

Don’t use your current weight for the category calculations, use your lowest ‘race’ weight entered during the past 60 day period.

This means adding weight will have no short term benefit in category calculation so you are unlikely to do it unless your weight really has gone up.

This means reducing weight might help your immediate short term racing but at any moment may have an impact on your category calculation and take you up a category ( just like winning races and improving your race ranking should do ) and will remain on your record for 60 days.

Looking at weight changes for regular (honest) racers I’m sure their own weight moves very little during the racing season. My suggested change will probably have much less impact on honest racing than it will to those who might be amending their weight for gain.

We are prepared to race at our correct weight - shouldn’t we try and do something to encourage weight dopers to follow suit?

Sure, but you improved the accuracy of your CP / W’ calculation. No issue with what you did at all, everything corrected itself.

The idea that if someone gets upgraded and they don’t want to be, they can just do an all out 3m effort to go down again is nonsense - unless they are correcting an unreliable existing CP calc. And if that is the case, great! It’s hard to build a curve off only long duration max efforts…

Its not presumed it can be replicated. The idea is to build an accurate CP curve and W’ for the rider - their physiological capability. It says nothing about what it thinks a rider can do after a certain about of work.

Outside of Zwift - if my CP is 310w, after 40 min of hard repeated efforts, I can probably only hold 310w for a few minutes. My CP is still 310w though.

There are many riders with FTPs that would put them at pro level, but riding as a pro is much more. Parking the skill element, things like repeatability and the ability to output power after doing 1000s of kilojoules of work is what sets world tour riders apart.

remember the goal of the CE model is not to predict who will win each race. Nor is it too give everyone equal chances of winning. The goal is to roughly group riders by a set of metrics that can be easily calculated and cannot be easily gamed. Within that group - let the best rider win.

(no need to divert this one to discussing the issues of static category boundaries that have been discussed elsewhere).

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I like this sort of thinking. Maybe the calc could use a weight range (say +/- 3kg). It would have to be secret though so people don’t game it, and then we get in to all sorts of moaning.

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Agreed 100%

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You’re going to get this no matter what!

Some very interesting ideas here, particularly dynamic categories and AI based automatic performance verification:


I don’t mean people get demoted for a single bad race, but there has to be a mechanism for people to go back down through the cats when they get poor results.

Any curve based on best efforts achieved over a 60 day time is bound to be unreliable by construction. How many people have actually done true best efforts at various time intervals? Hitting a hill in a race isn’t it, by the way. Except for possibly some special cases like the S4W hill climb and only then if perfectly paced and well rested/tapered.

I doubt that more than 1% of active zwifters couldn’t improve some section of their power curve inside a week if they set their minds to it.

The CP curve fit is a practical way of achieving a reasonable estimate, but holding it up as some sort of natural law or truth is a bit silly.

You can certainly go up one day and down the next in the CE model. Your last ride lasts for 60 days, but if your full curve used to calculate CP also depended on other data that was 59 days old, this will drop out of the calculation and change your CP again.

Exactly the same thing happens in the ZP W/kg cats where your best three rides might include one that is 89 days old. It’s not that common, but it definitely happens for people close to the limit.

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i also wonder about this. i haven’t seen any training plans or workouts on zwift or trainerroad or any of those basic programs people use incorporate max testing into them either

Two contradictory statements? Or a double negative I can’t quite work out.

The CP/W’ accuracy can be obtained very easily from little data, as long as there is some semblance of ‘max’ in there. That’s why it is so much better than the 20m calc. Of course all of those max efforts may not be true max efforts and a someone’s curve could be reading lower than their true potential, but it’s a tiny misrepresentation of ability versus the 3x20m model and as is immediately corrected with any subsequent effort, like the example given above.

I use the with Morton’s 3 parameter critical power model to calculate my CP is 148W, smaller than 150W. Why am I in category C?

Use the high North calculator and put in 3 max efforts. As we don’t see the exact Zwift calc, and which efforts are being used, it is more than fair to say that it could easily be calculating your CP 2w higher. 2w is less than trainer error from day to day!

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