Category enforcement - does it even work?

This is a big rider at 133Kg. I have been focusing on the ZHQ series races for the last few months so I frequently watch races in the Live mode of ZwiftPower. This rider was in a race I watched this week.

He is a frequent racer and his profile shows him with consistently high results.

Another idea what to do when you are freshly promoted up is to enter races with all categories visible. Then you can race with people of your abilities around you and just ignore which categories they are in.

This will not work for folks who do not race for the feeling of it but instead just want to collect digital trophies.

The above is what I did in past and will do again later this year once I can improve my fitness to previous level which was Cat B by 0.01 w/kg :joy:. Normally I am in the top 0.2 w/kg of C-cat.

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Tuesday’s race was a good one. You left me breathing pretty hard at the finish :slight_smile:

That 17:10 time slot is usually the most competitive race of the day. The winner in today’s race finished in 30:53 with 3.1 w/kg (245 watts). Second place had 2.7 w/kg and 265 watts.

I don’t know if you pay any attention to the site, but the rating system utilized on it helps me understand the results in races. they have a finer breakdown of categories so you can see the spread of capability levels contained within the Zwift D category. This rating method is being used on the new Club Ladder Racing Series. It’s worth a look.

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I see the winner of that 1710 today had literally just been demoted from C, back they go, they would have been close to a zMAP promotion on top of that ~3.1W/Kg for ~31mins race!

I quite enjoyed our Tuesday race too, despite the small field, probably because of the race dynamics around me (losing the lead trio; catching them back and wondering if you would catch me; getting ditched by trio again; seriously running out of legs and expecting you to catching me while I got to the finish on fumes)… Bit more dynamic than the Tiny Races!

are the numbers now taking 90 days instead of 60 as I have numbers on my power curve that are 64 days old, the zwift site is still showing 60 days so i assume there is something amiss either with the calculation or the zwift site hasn’t been updated

Zwift site is going to be updated later on today to reflect that change, showing 90 days instead of 60 in the label. The graph and data information you see is for 90 days. It’s only the label that’s missing the update.
Sorry for the confusion.

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What was this?

45 min race in group B and 7 of top 10 riders averaged more than 300 watts with two riders averaging 400+


What was the event and time, or event ID?

sorry was 35 min race. Event ID 3737371

I know its a race, but several complaints mid-race about the pace. Front rider was on their own for much of it.

I don’t see the issue here? What do I miss. These guys are in the correct category even with the old ZP categories.

Only one rider exceeded 4.2W/Kg for 20mins (but not enough for zFTP promotion), while nobody threatened the zMAP threshold of 5.1(?)W/Kg in the results, from what I can see.

I’m not saying it’s right, but those are the current boundaries, the top end of B is stronger than it used to be (as is C and D).

Its definitely at the top end of races I’ve been in, maybe we were unlucky with the weight of the field today and the pure watts. First 80% of that course is flat so watts matters.

It’s gonna be tough doing a flat race against the power of the huge guys who stay under W/kg limits due to their mass. The most recent CE change was lowering the zMAP threshold which moved many people up a category. Previous to that the CE algorithm was adjusted to arrive at a lower zFTP which moved many people down a category. It’s a mixed bag but zMAP is probably a better predictor of winning in most Zwift races. As a medium-mass rider with a poor sprint, decent MAP, and just OK FTP, I’m really looking for the rolling or hilly courses (not huge climbs) when I want to beat the big guys. It looks like you made it to the finish and then lost the wheels, which is kind of what I would expect unless you are an exceptional sprinter for your size. The categories are completely arbitrary so if you’re at the bottom or the middle or the top of the category, that’s the luck of the draw. I’m a hair’s breadth from the next category based on zMAP and if/when I make it to the next level I’ll probably get dropped after 10 minutes.

yep, CE actually has me flip-flopping between B and C, but I’ve got a pretty decent 1 min and 30 second sprint so favour short kickers, rolling courses and crits.
I was very much struggling to draft most of this course often getting pushed to the back, but now I see why given the watts.

Compare this to primetime OG Stage 3 just now with a large field size. Similar w/kg but very few over 300 watts and that race is 10 min shorter with three punishing hills to finish.

This week I’ve done the Zwift Hill Climb Racing Club event on the Volcano, done a 5.4w/kg effort on the KOM (7 minutes) which has set me all-time power bests from 4 minutes through to 9 minutes, and yet my zFTP has dropped from 306W to 298W (72kg). The same effort put my estimated FTP, by the judgment of, up from 311W to 321W.

I put my 5 minute, 12 minute and 20 minute power into here: Critical Power Calculator — High North Performance

And it came to within 5watts of my zFTP (I just did the Hill Climb too) so I had a new 5 minute PR also.

If your short duration efforts improve without a matching improvement in the longer duration efforts (above 15 min.), the system predicts your anaerobic capacity has improved which leads to a lower zFTP.

zFTP tries to predict the actual power around which your lactate threshold occurs, but in order to that accurately, it needs “good data”, i.e: maximal efforts both from shorter and longer durations. If your longer efforts are not maximal, it naturally leads to lower values.

I’m not sure what does, but clearly uses other methods, so comparing the values is not really productive.
(also keep in mind that might be using outdoor rides data, if that is the case)

Does anyone here know what claim their FTP estimation to be?

  • is it the 1h power?
  • is it the power around your lactate threshold?
  • is it the predicted power of your time to exhaustion? (i.e: if your TTE is 30 min., the power you can hold for 30 min., etc)
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You can actually select which method uses:


That’s the method used, but what I meant is what does FTP represents for them?

Also they have eFTP and eCP, but in other place they have CP = more or less FTP… it’s a bit confusing :thinking:

(anyway we are going off topic to something that is not Zwift related. I just wanted to clear what zFTP is and that comparing to is not really productive)

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