Hi, I notice this morning my cat changed from B to C after the ZRL race yesterday. Nothing particularly odd there you might say, but what is confusing me is I got bumped up to a B in the last 30 days so was under the impression I would be in B for at least 90 days. In many ways, now ZRL has finished it makes a limited difference as most races use racing score now. As a side note, all my PB power outputs have been gained in the last month so for the life of me can’t figure out the drop in cat. Any ideas are gratefully recieved
Were you promoted on zMap or ZFTP?
Its easier to drop zFTP and therefore bring you back under the category threshold by doing a hard short effort. so if you were 3.38wkg and dropped to 3.35wkg zFTP you would move C to B (im sure those were the numbers from memory)
You can drop zMAP its just not as easy.
If I went up in the last 30 days from C to a B due to exceeding cat limits, how would I suddenly drop down again within a month, when I thought it took 90 days? Have boundaries changed just me not being very bright and not getting it. Cheers for the reply
zFTP can change on a daily basis because it’s modelled based on best efforts.
For instance, you could go out tomorrow and reduce your zFTP by 10 watts by slamming a sufficiently cheeky 4 or 5 minute effort. I know - it sounds weird (and it is) but that’s models for you.
Having quickly checked what I presume is your Zwiftpower account, you are currently at 3.32wkg for zFTP. That is pretty much on the border so there is a good chance you were previously above that and your recent ZRL 4.1wkg for 5mins nudged that downwards.
Having said that, 3.7wkg for 20mins should put you into B. Previously highest I had seen was 3.65wkg for 20mins for someone to remain a C.
If you refresh your profile, do you remain a C?
If you want me to run some calculations that will be a pretty close approximation of where you stand in relation to the category boundaries, go to my.zwift.com and look at the Fitness section. Share the zFTP, zMAP, and both the Watts and W/kg for 3, 5, 12, 20 minute PRs.
I agree with Lee that the likely explanation is that you exceeded the zFTP number, but a new PR of around 5 min lowered your zFTP by just enough to slip under the boundary, without exceeding the zMAP boundary. If you were about to do a race series based on CE I would recommend joining B since there’s a reasonable chance you would end up there in the middle of the series.
Thanks for the response. I thought 3.7 would put me in B for certain, and in a ZRL in August a 3.56 put me in B, came to C after 90 days and then two weeks later (approx 4-5 weeks ago) went into B again with 3.6. With the numbers you quoted, think you are looking at me but here is the link ZwiftPower - Login
C high end is like Low B to med B now.
ZwiftPower is not a great source of data about where you stand in relation to the category boundaries since it doesn’t provide a way to see the exact weights you were when the PRs were set, and the PRs may not all be from events. For a more precise answer you need to pull the data from your zwift.com profile as I mentioned above, which is private so only you can access that.
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You set 90 day W/Kg bests yesterday for 5-11mins according to zwiftpower, now you’ve refreshed your profile. 
That will drop your zFTP, but if too much of an increase, risks a zMAP promotion…
Not that Category Enforcement is used for many races these days.
I cant see it affecting much, as you say it is all racing score these days, but I was just curious, so please peeps dont waste too much time on my question. For those who are bored at work, my stats from zwift are:
zFTP 232w zMAP 285w
- 5 sec745 w10.42 w/kg * 15 sec718 w10.04 w/kg
- 30 sec533 w7.55 w/kg * 1 min415 w6.04 w/kg
- 3 min316 w4.56 w/kg * 5 min287 w4.12 w/kg
- 10 min266 w3.82 w/kg * 12 min258 w3.71 w/kg
- 15 min258 w3.7 w/kg * 20 min260 w3.73 w/kg
- 30 min249 w3.53 w/kg * 40 min243 w3.49 w/kg
If that makes it any clearer.
So does the race that promoted me back into B not last 90 days any more if you get my drift?
Cheers
I have a funny feeling that 12/15/20 min wkg is making the model do some odd things… With 20min being higher than 15mins.
Didn’t even notice that, but those figures are dated last night so you may have hit the nail on the head :=)
Here’s my best estimate of where you are in relation to the category boundaries. Very close to both the 3.36W/kg zFTP limit, and the 4.1W/kg zMAP limit. There may be minor rounding errors in these numbers but you’re about as close to the B threshold as anyone gets.
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Very interesting indeed, that is razor close, thank you for taking the time to do this as makes it all clear and thanks everyone for the responses