FTP lower than expected


This is my first post, been using TR for a year or so though.

I am about to start a new sweet spot base block that will start tomorrow with an ramp up test. Today I decided to test my trainer to fine tune the setup and found out that the power I was outputting seems to be lower then expected for the speed I was able to sustain. I am using Virtual power on a dumb trainer with a magnetic resistance together with a speed and cadence sensor. The rear wheel is just barely touching the trainer wheel and I feel that I have a good grip. Also using a dedicated trainer tire.

The question is, is this normal behavior? Can I do anything to improve the readings? How accurate is VP for you vs real world?

According to Strava I peaked at 48km/h and gott an estimated FTP of 97watt. That seems a bit low for the speed.

The test was done on a tacx blue matic on setting 1 with a tacx speed and cadence sensor.


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Hi there and welcome!

Does seem a bit low, as does your heart rate.

But you only got 12 minutes into the test before stopping and warming down.

My FTP on virtual power was around 180 iirc. And 210 when I got a power meter. So you do get some significant variation.

My dumb trainer presses the tyre quite a bit harder than “barely touching”.

Have you selected the right trainer and setting in your virtual power set up?

Were you sweating blood when your legs caved in at 12 mins, collapsed over your bars and panted until the dizziness went away so that you could finally and feebly reach up to hit the warms down button?

FTP is just a number, if it is 97 then so be it, it used to scale you workouts to get the most benefit.


Yeah, Avg. Heart rate was low but I peaked at 180bpm before deciding that I had enough. I think FTP was set to 150-160 before the test. From the effort I thought 97w was way of. I will probably go harder tomorrow as this was a pre test to see if the setup was correct, let’s say that I stopped at like 85-90% of my capacity.

Yes! Everything is correct in the app and the right trainer is selected. I have been on this app and trainer for lite over then a year. Had a a break from TR now during the summer but staring to miss the structured training that I had on TR. I never gave the actual numbers any real thought until now.

I having trouble finding the power curve for my trainer also. It might shine some light on the matter.

Barely touching is maybe wrong, I can feel the resistance and do not feel that the tire slips, so it should be ok.

When it comes around, I know it’s just a number that I can train with, but I was hoping to have it be close the the numbers that I have on the road. After the test tomorrow I don’t want to change anything, but if I can make some changes before to have the most optimal and correct reading, I would be happy to do that.

:joy: gotta love those FTP tests! Stuffed if I know how I used to do the 20 minute version.

Was that 150-160 setting your FTP on that setup before you had a break over the summer? If that’s the case that sort of drop isn’t unusual.
Fortunately, it should shoot back up pretty quickly.

In regards to Virtual Power, I found it was within 10 watts most of the time when I used my old fluid trainer. Pretty good really considering all the variables. YMMV.
If you’d like to test the difference at some stage you can always do a test using a borrowed power meter. You simply record the ramp test on two devices with a different power source for each device.
After you’ve got the two data sets you can take you’re max 1 minute power from both devices and multiply it by .75 to get your FTP’s.


Okay, that makes more sense, and I think the result reflects your performance on the test.

Email TR support about finding the right power curve.

Check the tyre pressures, ditch the heart rate monitor, and go past where you want to stop until you literally cannot turn another pedal. Yes it’s uncomfortable, but of 19-23mins only the last three or four are the worst :+1:

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I previously used virtual power (Cyclops Fluid 2) on TR and whilst I’m sure I benefited from the structure and the sessions, I found the consistency of my setup and the numbers I was able to hit fluctuated quite drastically.

Last year I purchased a Tacx Flux and that has been a game changer. My previous FTP had been 325. I estimated 285 for the Flux. My first Ramp Test gave me 268. I took 268 and it was pretty much spot on. Sweet Spot Base was a whole new ballgame on a Smart Trainer.

To summarise, I wouldn’t be surprised if you saw your numbers going up and down, especially if you have to pack your setup away after each session.

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Love FTP tests, they are the best! No Pain, no gain, right?

No, i think it was lower then 90w, or around that number.
The thing is, last week i did a 20min FTP test and got and FTP of 30w, that’s why I now obsess around the numbers, I found out that the tension on the rear tire was set way to high, so after releasing the pressure of the trainer it booth feel better and more “road like”.

I do see an increase in FTP from previous training blocks, but i started to think that i had to much pressure on the trainer wheel even then.

As 30w wasn’t a realistic number so i did a self estimate from my outdoor rides and came up with 150w. I used this site to give me an indication on a realistic number.

But now, after sleeping on the numbers, I feel that 48km/h and getting a peak of 100-110w so early in the test was is a sign that the resistance is not sett correctly, I mean, that’s a proper sprint on the road. I literally ran out of gears and could not hold the cadence. That has never happen before, so I will try to raise the resistance on the trainer. And do a final test today.

I will probably upgrade to an smart trainer this year when the indoor season kicks in, the weather is to good now for not riding outdoors.

When you say you’ve been using TR for a year, has it been on the same setup? If so, and you’ve been completing workouts successfully with FTP set at 150-160, then clearly something has changed about your setup. Tire pressure, low battery on your speed sensor, how the bike is mounted on the trainer - something is different.

With virtual power the actual number doesn’t really matter too much, what matters is that it’s consistently from one session to the next. Doesn’t really matter whether 97W on your setup translates to 97W using a power meter, what matters is that if you do a workout with FTP set at 97W on your setup then you’re getting a good workout. I.e. Endurance feels comfortable but still having to work, SS feels uncomfortable but manageable, over unders are getting really painful, VO2 and above you’re wondering why the interval timer appears to be counting down in slow motion as your legs scream at you to stop.

ETA: my advice would be to do a few workouts at the FTP from your test, you’ll soon know whether it’s in the right ballpark, if it’s not then either test again or just adjust FTP to a level where hard workouts are tough but manageable

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Regarding virtual power, you might just as well measure effort in stars or ponies. It’s good for training and scaling the Trainerroad workouts, but useless for comparing to anyone else. If you stick to virtual power, keep everything consistent while doing training blocks. If you want to compare with others, you need a real power meter.
Real watts can be 0-300% higher or lower than virtual watts, depending on tyre type, tyre air pressure and roller against tyre pressure.

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He said he had a break from structured training over the summer in the second post. I’m down with your advice, but that’s the big difference in setup.

As an example. My first go at TR had me starting around 160 and ended with 248 on virtual power when I broke my shoulder in my first XCM race.
3 months later I was starting from 170w. This second attempt had me end up around 260w with an actual power meter and that dropped by around 11% after a couple of weeks rest.

Once you ditch the numbers and get on with the training you’ll get faster. I totally agree with that sentiment.
Smart trainers are awesome when they work properly, but they aren’t needed.

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