Embarrassing Zwift FTP Fail

After a few weeks of riding on Zwift i have an estimated FTP of 187 (crap, i know) using a Tacx smart trainer. Been wondering how accurate that was as its only based on a few races and hill climbs so decided to do the full FTP test.

Now being a mountain biker i’m pretty good at judging my pace on climbs so i don’t blow up but clearly have no idea how to do this on the flat. After 30 mins of warm up i hit the 20 min test proper. Went far too hard from the off, and started to fade 4 mins in. 5 mins i’m down shifting trying to keep going. 6 mins I’ve gone light headed and stopped.

Utter failure.

Just going to assume the 187 is about right and trust zwift will update this if i get better over the winter.

FTP tests are as much about knowing how to do the test as it is about the fitness.

Give it another go in a few days using the experience you now have.

It doesn’t really matter whether it’s ‘right’ apart from bragging rights. The whole point is that it’s a fixed, repeatable point to base your training around.

If your trainer under or over reads your power it’s not a big deal as long as it is consistent.

Takes a few goes to dial in pacing a 20 minute effort, start low and build on it and you’ll soon get a feel for it.

E2A: In the meantime just stick with the estimated, or try a TrainerRoad ramp test.

As above the number matters not, it’s the consistency of the test that counts.

Or try again with proper pacing in a few days?
My preferred tactic is to start at what feels just above tempo, 5 mins later a touch more, 5 mins later to what I think I can sustain for 10 mins, 5 mins left if I can up it a bit more. Aim is not to be a sprint at the end but still have emptied the tank.
The more you do it the more you get used to the pacing and effort needed. I hate doing them but do it every 6 weeks. My training plan also has a build up week (easier than normal training week)

I wouldn’t worry, you can always give it another go. Just give it a few days of easy activity before giving it another blast.

I find the tests quite mentally stressful. I’ve dropped out of a few part way through and also not started some. I’ve found them a useful marker, but they’re not everything.

I wouldn’t worry either. Zwift will update your FTP even through normal riding/training. Don’t get too bothered.

As said above, don’t worry about it, it’s just a starting point/reference. You will get better at measuring the effort for a test, and therefore get better results in later tests even with the same fitness.

Last winter I was happier hitting reliably good average outputs in the races or on hot laps of the different circuits rather than doing the FTP tests. Zwift will automatically take your best 20 min effort from any session, which is a good way of doing it without the fuss of an FTP test.

Which trainer is it and how much do you weigh?

With regards to Zwift automatically changing your FTP, does it know what is a Zone 2 ride? Can it differentiate between easy rides and actually training intensity rides?
Some of my training / recovery rides will be at zone 2, some of it is sprint training where I can be at zone 3 for 95% of the session but with 7 max efforts. Would Zwift be able to know not to include those or to only use it as a % of FTP? Always wondered how the auto update thing works.
I use Sufferfest myself, this keep your FTP and your other metrics the same until you re-test.

Thanks all. I’ve done a few rides beasting myself on climbs that have taken me over 20 mins to do, so i’ll assume my 187 FTP is accurate. But still might have another go in a few days using some of your tips.

Woodster: I think zwift takes your best 20mins average so doing lower level z2 rides shouldn’t change it.

Fibre: Its a Tacx Vortex and i weigh 83kg. So this gives me a w/kg of 2.25 or class D. Which is about right as i am an untrained occasional weekend warrior – hence the need to start upping my game.

Erm…it’s better than mine!! But I’m doing the 4 week ftp builder. I manually upped the ftp to make the first couple of weeks harder for me, and it is definitely working – might need to drop it slightly at some point though!!

Ha! This sounds familiar!
I did the 12wk ftp builder around this time last yr. I think my starting value was 191w via the ftp test and i upped the ftp value within Zwift for the training plan as i found it was a bit too easy.

After 12wks, I was excited to redo the ftp test. I felt tons stronger, but did really badly. Zwift was setting the resistance too hard and I was battered after 10 mins. I couldn’t work out how to adjust the resistance on the fly.
At the end of the test after 12 weeks of supposedly hard training, my ftp went up by 3w!! Lost interest at that point.

Blackflag – try doing the FTP test holding your estimated figure (FTP/0.95) and then just increase your output towards the end if you’re feeling strong.

timbog160 – rather than upping your FTP value you can just use the Bias setting on the app game screen to increase / decrease the difficulty by 10% on the fly.

^^ Ohhh thats a good idea! Ta

Is there no 8min or Ramp test in Zwift? 20mibs isn’t great for folk that aren’t into TT or Tris

Is there no 8min or Ramp test in Zwift? 20mibs isn’t great for folk that aren’t into TT or Tris

Don’t know if there’s one available by default, but you can always create your own like this.

If your FTP is 187W, you should be right on your current limits holding ~197W for 20mins up one of the big Zwift climbs.

If you still feel like you’re not going to die at ~15mins, increase the gearing every 1min or so.

You could try using the free TrainerRoad trial and their ramp FTP test. It’s unpleasant but far less so than a traditional FTP test.

Or a Zwift race is a good estimation if you can find one that runs for about an hour.

After 12wks, I was excited to redo the ftp test. I felt tons stronger, but did really badly. Zwift was setting the resistance too hard and I was battered after 10 mins. I couldn’t work out how to adjust the resistance on the fly.

Zwift shouldn’t be setting resistance for the ftp test, it needs to be in slope mode, so you have total control over pacing and power output rather than the trainer setting the resistance. I suspect it’s supposed to do that automatically, but they do seem to have glitches on stuff like that.

If 187 seems about right from riding around then aim at holding 210watts (which would be a FTP of 199). Dial it back slightly as you go or slightly up.
If you can go a lot harder in the last 5 minutes at that you are way down and should probably be looking at 220 to 230.
My Zwift FTP (based on races) is a good 20 watts lower than my tested FTP as I don’t do many 20 minute stints where there isn’t a long enough lull to break the power down.

From what I’ve read your actual FTP is relative to your weight so can’t be compared to others as a number alone. It’s the Watts per KG that’s important. Especially for climbing.

Zwift shouldn’t be setting resistance for the ftp test, it needs to be in slope mode, so you have total control over pacing and power output rather than the trainer setting the resistance. I suspect it’s supposed to do that automatically, but they do seem to have glitches on stuff like that.

Erm. I can’t remember exactly what happened, as it was almost a year ago.
But, I definitely remember being unable to get to the power I was aiming for. The resistance was either too high or I was having to spin too fast to bring the resistance down, which was unsustainable.

I found plenty of posts online saying the same thing and that within the companion app, there were + and – buttons available during training workouts to adjust the resistance and this is what I should have used…
I’ll try it again at some point…

Warning I’ve never fine an FTP

But surely all the advice about holding back a bit for the end is wrong. I thought the point was to make a steady effort?

But surely all the advice about holding back a bit for the end is wrong. I thought the point was to make a steady effort?

Ideally yes, you would just do your maximum power possible constantly for the 20 minutes.. but in reality you don’t know what that figure is until after you’ve done the test. It’s an average over 20 minutes so if you go a bit harder at the end (if you have some extra left) the result will be similar to if you spread the extra effort over the whole session.

Just enter a race that lasts for just over 20mins.

That’ll get you your FTP

Nothing like trying to beat and impress total strangers on the internets as motivation to go extra deep.

(Register on Zwiftpower)

Or you could just ride a few hard events, zwift will estimate and upgrade your FTP as appropriate. I’ve never done a proper test but the number it gives me seems quite realistic (it’s probably a little low, but I’ve not pushed myself much).