Yet another Cat C vs Cat D

Hello fellow zwifters!
I have read FAQ on the category enforcement but I would like to hear your opinion on what’s going on with my profile.
I am an average Cat D zwifter as proven by this screenshot
However I am enforced into Cat C because my zFTP is 217w and is just above 2.7 w/kg. My profile shows that my max power over 30 min is 193w but zFTP is somewhow 217 w (!!)

Comparing myself vs recent Race Scotland events
(cannot include links) on zwiftpower
I see that top 50% of Cat C riders produce 3.0-3.9 w/kg while I only have 2.54
At the same time top 50% of Cat D riders produce 2.3-3.1 w/kg meaning that I will have a chance with my 2.54.
Could someone with an experience in category enforcement rules please suggest what can be going on here or should I go to zwift support? Clearly there is no point for me in trying to race in Category C.

Whether it would definitely result in your zFTP reducing enough for you to become D again, I couldn’t possibly say, but compared to my stats I think you have lot of potential for improving your sub 3min power curve.

Get a good warmup, perhaps outside Zwift and then absolutely smash a 3min effort up something like Thursday’s ZwiftPower - Login to the KOM banner.

Welcome to the forum!

Try to do some shorter harder efforts in the 3-5 min. range. That should steepen the power curve a bit and decrease the zFTP.

Sometimes when the older best efforts “expire” (60 days), it bumps up the zFTP too much because the power curve will remainin too flat.

It can also be caused by the fact that 10 min effort is less than 12 min or 15 min less than 20 min power and then the zFTP projection has an upward trend. These are not seen in the Zwift Power profile but you could see it on sites like In any case, bumping the short term power should solve the issue for you.

You had 2,7 and 2,8 W/kg for approx. 15 minutes- Tour de Zwift, 9th and 10th Feb - I believe this is why zFTP is how it is. Don’t forget - Zwift CE are different from ZP categories!

Many thanks for advices - yes, I did 2.7-2.8 w/kg in 15 min but I really do not feel like I would be able to sustain 2.7 for >40 min (which is what zFTP is supposed to represent).
I will do short interval workout to push short end of the curve, hopefully it will reduce my zFTP altought I still find it counterintuitive!

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You seem to be there where I was in the last 3 winter seasons (ZP only, no CE) - started in D, some good races, D almost C, later C.
Bottom C is not much fun and I am not going to be stronger (age 60+).
My motivation was to beat 1/3 of the starters, this season it is to get C again!

Ride on!

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Update: I tried to do shorter efforts but ended up improving my 20min and 30min Peak Power. However this reduced my zFTP from 217 to 208, however I am still in Category C. Seems like thinking about trying do a couple of races was a bad idea, will stick with group rides then :frowning:

This outcome means you didn’t do 3-5 min max efforts. If you did, you wouldn’t have set PRs at the longer durations. If you feel like trying again, I suggest doing Volcano Climb. Do the approach strictly as warm up, then when you reach the climb, go all out for a few minutes and then quit.

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75 year old here that definitely does not like being forced into C.

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Will try, thanks!

Remember you are a ZP cat D so choose your races carefully and you can race as cat D.

You are only cat C under Category Enforcement (CE) races - although they are now the majority of races.

Changing weight from 78 to 80 kg helps, too…
IMHO he is C.

Even without that small 2kg increase and his new 20 min power PB he is still very much under D cat limits in ZwiftPower. He is not even ‘nearly C’

I think we all know that the CE power curve calculations are throwing up some odd category calculations and I think this is one such case. [i’m now not 100% on this ]

The CE system requires max efforts at various times and I think the OP has been pointed in the appropriate direction.

EDIT - IMHO potential to be a Cat C but currently a ZP cat D. Possibly Cat C under CE, if CE is picking up what it is supposed to ?

this is where the lack of transparency comes into play with CE

So far every time we see “odd” calculations we find either some big efforts in non races or weight adjustments or faulty power meter data.

Looking only at ZP I would also say Cat D

My eFTP on Intervals and my zFTP are now in agreement.
I’ve been doing hard workouts and races.
I like that Zwift uses the power curve but it is maddening that hard efforts have the affect of lowering my zFTP.
Intervals does not show my eFTP behaving like that.
Hard efforts increase FTP and a period of slackery causes a decrease.

That is just the way the formula work. You will notice that if you use the original formula in the paper.

Any change under 5 min will have an impact, so if you don’t have a good power graph under 5min it can over predict.

He is 2,39 W/kg, that is 4% under the C.
Weight change 78 to 80 is 2,5%.
And he has 2 15 minutes results with 2,7 and 2,8 W/kg.

Is it really “very much under the limits”?

The ‘very much’ was not used to suggest he was a long way under the Cat D limits it was used to emphasise that he is under the Cat D limit, albeit close to the limit.

You considered him a Cat C, that is fine and CE considers him a Cat C.

I consider him a ZP Cat D as does ZP and was trying to inform him that ZP races as a Cat D are available to him.