Racing Cats need some adjustments Cat A and B

3 minute power has no bearing on category enforcement.

My take, they have tried to shoehorn a system in to support power based categories and it fails to work as they are not aligned.

The idea that a strong short effort models out to a lower long term effort kind of makes sense.

But when you try to chop that model into segments (or categories) to fit a power based category, it falls apart as a good short effort will remodel where you sit across the power boundaries…

Slightly disingenuous there @James_Zwift ?

3 min power has an impact on the power curve and/or CP model - That will impact the zFTP model which in turn effects cat enforcement. So yes, short term power has a huge bearing on zFTP.

Im fairly sure, zwift staff have said the exact same thing I have in a number of other threads when this was raised…

No it has not (impact on zFTP). For more than a year probably.

3 min power impacts the curve for 4min & 5min etc.If you are improving 3 or 4 or 5min they are all bringing down zFTP?

A good short term power impacts zFTP?

Are you really going to argue semantics over the broken system about which exact minute the model kicks in at, when everything that goes on before it still impacts it?
You comment like everything before the exact second it kicks in doesnt matter - All the effort before it is what gives you the number.

Sometimes the hard thing when it comes to the way it all works though is that this is more a one size fits all approach.

If you break down the racing we have

  1. Sprint races
  2. Short Endurance
  3. Long Endurance
  4. Climbing
  5. TT

So kinda 5 ways to look at it but we are using 2 prong approach using ZMap and ZFTP. The thing is a person with fantastic 5min power who wins sprint races is normally a terrible climber. That person is Cat A regardless.

To complicate the whole thing a rider really should have multiple cats based on the type of course/race. A Cat A rider for a sprint race who is a Cat C for a climbing race may actually be more incline to race a mountain race knowing they are able to compete than in a Cat A climbing race getting dropped.

But that is very difficult to do so we are where we are and really the best approach at the moment is looking at the goal posts and making some shifts to try and 1 forcefully encourage those at top of Cats to be pushed up and at the same time hopefully narrowing the cats to bring along closer competitive racing.

hopefully my team captain sees that before anyone else in my division does

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Something doesnt add up - From within the last year. Either we are talking cross purposes or something is happening that is unexpected.

Example - Only improvement to the power curve was 3:00 - 3:30 - Resulted in zFTP being lowered. Its 1w in this example, but go into my power profile you can see short 3-5min efforts have dropped zFTP. Im happy to throw up any of my data in public if it helps.

Edit Just to add, that image is not me its someone else, but it correlates with what others are seeing & I have seen in recent weeks\months with my zFTP.


I was merely stating that your 3 minute power doesn’t impact CE.

(Definitely not questioning your sincerity here)

If you set a 3 minute PR, your zFTP will almost certainly go down a few points. Try it and report back on your results. I’ve seen this on many occasions having discussed it with club members, people on the forum, etc. I’ve never seen a counter-example where that did not happen. Other times around 3-5 min should also have some effect.


Ignoring all the fluff that goes on here. There has been some genuine ideas, suggestions, evidence, feedback what ever you want to call it.

You are a staff member for Zwift. So is anything of this information useful at all to improve the overall Zwift performance for racing? Is it anything that has been passed on to investigate further?

Like I appreciate you replying to posts but you have not really made any comment in regards to what the root was of me making this post.

Maybe you arent the right person but you are representing Zwift here so be nice to know if you have passed this on

But are you sure that in these cases that someone riding for a 3 minute performance, that the 4 or 5 minute metrics weren’t also changed (improved)?

I was merely pointing out something factual that had been misrepresented.

We’re aware of the various conversations in relation to category enforcement.

I’m not going to get involved in the merits of the system we use as it’s been done to death a thousand times over.

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Ok so its just getting ignored and the feedback is not worthy.

Got it

Poor customer service there James to just ignore something because you think its be done to death when its an actual issue right now and getting worse.

I wasnt asking you btw to personally get involved. I asked purely was it passed on and looked at so we know that we actually have a voice that is being heard

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Not wanting to get into loggerheads here, I believe you fully understand the point that was being made and how your reply whilst accurate in a narrow sense can also be seen as inaccurate in the wider sense.

Your deleted post was leading to that…

Short term efforts will not directly impact CE
Short term efforts will impact zFTP
ZFTP impacts CE

So both statements can be correct.

But in the wider overarching context, a 3min effort can impact CE via zFTP change.

Would that be a correct statement?

Pretty sure David has said previously that power at less than 5 minute duration is not used in zFTP calculations

Kind of.

  1. The example above shows there is something in the short range power that will impact zFTP
  2. James deleted post just basically said the avg from the period before will Impact the modelling.
  3. The model might not start taking its first point from 5/6/7mins but all the work through 1-5mins sets that point so does impact it.

I’m fairly sure that short term power improvements add to the data the modelled power curve uses, which inturn impacts the data points which zFTP uses.

It’s night not be directly impacting it, but when it all comes together it does.

In my own case, I did not set a 5 minute PR when I set the 3 minute PR. zFTP went down 20W. I don’t know about 4 minutes. The anecdotal information I have from other riders is not that detailed. Since the formula is a secret, there is of course significant risk of error when reading the tea leaves without really knowing how it works.

I don’t understand how someone can have 3 min PR with no change in any other duration. Dude really saved it for that 3rd minute I guess.