FTP Confusion
 

Hi there.

Just started to learn about FTP stuff for cycling.


Did my first FTP test on Zwift.


I am uncertain as to what my FTP number is...?


Is it the "Weighted Avg. Power" (158) from the "Power Curve" section of Strava Premium or is it actually the "Estimated FTP" (171) found in the Best Efforts Power Curve section found under Training->Power curve...?

Thanks,

Sparky

It's the average of the power you produced. Not weighted average, just plain average.

Thanks for the quick response Seattle Forrest

So I will go with 171 as my FTP according to Strava's report.

Much appreciated,

Sparky

When you did the FTP test on Zwift didn't it tell you at the end of the test what your FTP was? I just did the test this past sunday and it told me what my FTP was.

Hi em.jay.el

Yes - it flashed on the screen - but I didn't remember the number.

I thought it would be easy to find in Strava within that ride data... but I just can't seem to find that information other than what I mentioned above....

Thanks,

Sparky

Go to the workout screen and it shows your FTP from the test in IIRC the lower right corner

I have no idea how Zwift conducts its FTP tests.

If they have you do a 20 min test, your FTP is typically set at 95% of the average power for the 20 min test.

If its a 1 hour test, your FTP is 100% of the average power for the 60 min test.

There is a little more nuance to it (it depends as well on whether it was a "good" test, you can usually assess this by considering your perceived exertion, HR and the "steadiness" of your power output) but that's the gist.

However: if your weighted average power for the interval is quite different from your average power for the interval, this means that you did not have a "steady" power output but instead a "surge-y" power output. "Surge-y" power = bad test. The exception to this would be if you are looking at the weighted average power for the entire workout, and the entire workout includes warm up, cool down and other bits of power output besides the FTP test interval itself.

Tried to post a link to a screen capture - but a message pops up that states I must have at least 10 posts before I can post a link...

Sparky

There is no FTP category in the lower right hand corner

Sparky

Not my screenshot but it should look like this
https://support.zwift.com/hc/user_im...u--fISSPCA.png

Sorry for the delayed response - the forum rules wouldn't allow me to post another post - I had to wait 24 hours.

Also - had to remove your screenshot - as a forum rule popped up stating I needed at least 10 posts before I could post a url...


Now I see the part of the problem.

I was looking in Strava - in the lower right hand corner.

So... Strava's Power Curve section estimates my FTP @ 171, Zwift tells me it's 165.

Although these numbers are close - which one do you think is more accurate?

Thanks,

Sparky

It won't make much of a difference; go with 171 and dial down if you find that after many hard tries you seem totally unable to finish your workouts.

FTP is your power until you reach to lactate threshold. That could be 35 minutes, it could be 90. Over the years it devolved into average FTP for an hour, but its technically not.

Strava, Zwift, Trainerroad, and other companies all have tests to find your FTP but none of it is accurate unless you know your lactate threshold. Finding your lactate threshold isn't easy so people just use an hour as a baseline. Really FTP as a standard should be abandoned for something more concrete.

At the end of the day, FTP is the number we use to set our zones for training. I move mine around all the time without testing. If workouts are too easy, more it up, if the oppo move it down.

I would go the other way and use the swift number. The calculation is based on the specific testing protocol used. The strava estimation factors in the surges done before the effort to get an estimation which would be more variable when retesting in the future. If you find the workouts too easy using the swift ftp then you can bump it or increase the bias

I would use the number from the actual test. Looking at my "estimated FTP" for the last 6 weeks on my Strava Power Curve, it's exactly equal to my best 20-minute power for that same period. I know from experience my real FTP is more like 93% of 20-minute power, so I'm going to say take the Strava number with a grain of salt. Granted in OP's case 6 watt difference is not much, but I see no reason to do an FTP test unless you're going to use the result to set your FTP.

I think it depends on what you are going to use the number for. If it's just a number, and you want to see if you are getting stronger, then pick one and stick with it. I use trainerroad, and all the workouts are scaled to ftp. I found that if I stuck with what I tested, the workouts were too hard and I didn't get anywhere. So I set my ftp to a lower number and I think I am making more progress now. I think part of my problem was that I chose the 8 minute test, and I'm more suited to that test.

Don't worry too much about FTP.

WebDAV is where it's at.

This seems the best advice for me at this time.

Chose 171 and will use this as my base measuring number.

The FTP test I did was 1 hour... :giver:

Thanks everyone for the advice and suggestions - much appreciated

Sparky

the zwift ftp test is 1 hour total including warmup and cooldown but the test is a 20 min test

Yes - thanks for correcting/clarifying this... :thumb:

Sparky