Zwiftpower Cat C, Zwift Companion App Cat B

Zwiftcompanion app upgraded me to Cat B this month when Zwiftpower, downgraded me a couple of months ago to Cat C after two months of the bike. I use Xert gives me a FTP 211, and the new zwift power matrics gives me FTP 247, numbers that I had more than a year ago.
Also, I have noticed that zwiftpower those not updated the activity tab in my profile.

Zwiftpower and Zwift category enforcement use different methods of calculating FTP. Zwiftpower FTP is the average of 95% your 3 best recent 20 minute efforts, “zFTP” used for category enforcement is a calculation based on a curve that looks like this, where the zFTP is the power where the curve goes flat at long durations. This curve is supposed to model your absolute best possible constant power for any 1 given duration when rested.

Zwift tries to fit the mathematical formula behind this curve to your best power data from any Zwift rides in the last 60 days. It searches for a few points in all those rides that look like they are your maximum efforts and then calculates the closest curve that fits those points. This means that the curve won’t be so accurate if you have not done any all-out efforts at different durations, for example if you have only done 30 minute steady rides at roughly the same power throughout the ride and no hard efforts at shorter durations the fitted curve will be quite flat and zFTP may be too high.

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Thx Chris. Maybe it’s because of that. After my hip injury, I have been taking it easy and my numbers have dropped. Plus in the last few months average ride time also dropped from 8-10 to 2 hours a week. Zwiftpower put me in C and I feel correct. Most races in C’s are hard and not always easy to stay in the front group. Now I have to race in the B’s where I was struggling even in my top cycling form ever. This kind of destroys the fun of zwift. Don’t interpret this badly, not that I did not like getting to B and racing in the B’s in ZRL before my injury. It was a blast and I improved a lot, but I was dedicating a lot of time to it. Presently my 20min power is 3.1 on a good day, very far from a B rider. Anyway hope they come up with a better formula since racing is what justifies paying for zwift for me anyway.

Your zFTP number will be more accurate if you can do a few max efforts at different durations. I recommend that you first try a max 3 minute effort and see what that does to the zFTP calculation.

Thx for the advice. Will give it a try.