FTP test - what should I expect?

Being new to cycling and Zwift I decided I needed a measure of progress against my fitness - seeking to get back into shape and lose some weight after ~5yrs exercise-free after a knee injury caused by too much running.

So, mid January I did the 45min FTP test, leaving my Tacx Neo in ERG mode and got a not entirely unexpected low 125W FTP score (Strava reported it as 131W weighted average). Mid March I decided to measure progress and (this is where I went wrong I think) opted to try the shorter ramp test which resulted in an FTP of 182W (Strava reported weighted average of 145W). Last night I tested again, reverting to the 45min FTP test…and was marked down to 154W (weighted ave 152W).

I’ve spent the last month doing a consistent low/moderate intensity ride daily (1.5hr duration), using a training programme which operates on a percentage of FTP (Zwift controlled). The programme was chosen to target fat burning heart rates rather than much else. I’ve felt the ride getting easier and my heart rate data supports that - it was setting effort on the basis of the prior FTP of 182W.

I think the ‘answer’ I’m looking for here is that the ramp test isn’t as accurate as a longer test and so the 182W figure was always suspect, but would be keen to gain further insight. At the end of the day I’m looking for my FTP to give me a relative measure of progress (so should likely stick to doing the same test!) but also as input to set the intensity of future rides.

I think the shorter FTP tests which do a percentage of 20 or 45 minutes efforts become more relevant the fitter you get. You can see that in your progress already, with your 45 min test improving by 30 watts in 3 months you are getting closer to that initial shorter test you did. In another year shorter tests will get even closer to your real one hour power output FTP.

Personally I don’t do FTP ‘tests’ because I don’t like tests (other than what I can muster up during a race), and Zwift will auto-calculate your FTP as long as you do a 60+ minute effort. With the shorter ramp test result of 182W you have from before it will be a few more months until you see your 60+ minute efforts surpass that number. Or you could just delete it if you want to see your FTP number climb as you do 60+ minute efforts from here forth.

Never heard of 45 minute test, only 20 or 2 by 12 or 2 by 8. the ramp test is flawed as it is too short on Zwift. a real ramp test I do is 5 watts per minute increase not 20 or 25.
Stick with 20 minute test. Just know that as a new cyclist, your ftp will be lower because you haven’t gotten accustomed to long hard efforts. Enter a few races to keep hitting some high numbers.
and hang in there. Stick around.

The 45 minute test he’s referring to is Zwift’s short test which has a warmup, a 20 minute test, and then a cool down. This is the traditional 20 minute test where 95% of your 20 minute effort is your estimated FTP. There is a longer test which just has a longer warmup period.

Thanks all for the replies to date - all makes sense. What seems to be the case is that when using a workout/programme, or more especially one which is based upon a percentage of FTP thereby targeting certain heart rate zones, Zwift doesn’t register any improvement in my fitness/performance so even doing 1.5hr rides daily it wont adjust my FTP.

For my purposes of blending fat burning with gradually increasing my fitness I’d ideally want to be able to directly specify a workout in terms of heart rate targets, but I don’t believe this is possible. To take this into account I was hoping to use an occasional test to reset my effort levels - lesson learnt that I should at least be consistent with whatever test I’m using, and if I cared about comparing my own stats with others then using a more standard 20min (within a 45 or 60min workout) test would be the answer.

For the weekend I used my usual programme and overrode the tested FTP of 150 back to 182 knowing I can easily handle it in the context of the percentages involved (I’m not kidding myself that I have actually achieved that 182, simply using it as a relative number in adjusting intensity).

With a bit more time and confidence I’ll actually start using Zwift for group rides