I just got bumped up to C and at 74, it’s seriously no fun riding alone. I don’t win any of the D races but at least I get to ride with a group for most of the race. If I look at my activity, it says my zFTP is 206 and at 78kg that calculates to 2.641. The upper limit of D is 2.625 and I’m over that. So, I check my weight and change to 79kg so the new wKg is 2.608 and under the D limit. But I’m still forced to C. Last race I did, I would have taken 15th place in the D group… Next to last in the C race I was in. So, I’m not trying to cheat anyone, just have a more enjoyable ride. Why isn’t the forced category changing?
I believe it uses your average weight over the past 90 days, so you will have to wait a while before it downgrades you.
Simply increasing your weight hasn’t recalculated things for some time now, you have to set pure Watts bests at the new weight.
Your power profile on zwiftpower looks very flat 5-14mins.
At ~2.9W/Kg for 5mins, you are a fair way from the pen D threshold for zMAP (predicted power for ~6mins).
If you do a 5min effort that improves your current best from the last 90 days, your zMAP will increase and might still be under the 3.2W/Kg threshold, which in turn will lower your zFTP a fraction and almost certainly put you back in Category Enforcement D.
Alternatively, your Racing Score is ~167, which very comfortably puts you in the lowest pen E. Join some Zwift Labs races that use Racing Score (Herd Beginner Races, Tiny Races, selected ZwiftHQ Zmonthly races, ZwiftHQ Crit Club races).
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Well, great information… although I’m going to have to think about improving my 5 min best so zMAP will go up and zFTP go down! 
Thanks for the advice!
Zwift Racing Need to Knows - #2 relevant CE info
Fitness Metrics FAQ specific fitness metrics info for those in need of deeper understanding… those listed max effort intervals should ideally be maximum efforts. take the faq at face value because it’s quite well written
Steve_Cl: Awesome!! It worked. I did a workout with a 15 min free ride so it would show me my running average watts and time. I averaged 231 (had to really slow down at the end) and ended up going from 206 zFTP → 203 and 223 zMAP → 228. I checked a race event and it suggested “D” for me!! Thanks so much for the advice. I would have never thought of that!
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S_A_Cestria_CC: I’ve read those FAQ’s and they are helpful. However, it always talks about “maximal effort” but never really defines what that actually means. Is it with 5% of your peak power?.. 10%?.. It would really help to know what they mean with regard to their calculations.
It’s the most you can do over that amount of time. Percentage of peak power will depend on you: your physiology, your brain, your training history.
Failure at those efforts can be extremely helpful. You try what you think is a 5 minute max effort and you fade significantly before the end. You try again a little lower and see if the average is a little higher. Fail a lot and you will develop personal insights.
it means having a sit down in the shower afterwards, or a bucket ready
zftp/zmap are based, sort of, on the concept of Critical Power. Critical Power builds a physiological profile of an athlete based on a few key intervals (such as those listed in the faq), or it could be 3/5/12 minutes or 2/6/20 or whatever. for the profile to be accurate, the efforts have to be 100% maximal for those durations, or as close to that as you can get because performing a 100% maximal effort over any duration is a very difficult thing to do
in models like these, submaximal efforts can sometimes lead to a misrepresentation of your actual ability. that’s why the faq is asking users to push hard
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