FTP drop after moving from Low volume to Mid volume plan

I’ve got a puzzle.

At the end of last summer season I decided to give a mid-volume plan a go. I did a ramp test before starting SSB and tested with an FTP of 281. (I’d just finished doing low volume maintenance plan with plenty of outdoor riding - the maintenance plan has lots of short, sharp VO2 max work)

Went through SSB 1 and SSB 2 (I skipped re-test in the middle because that fell Xmas week)

Then started sustained power build 4 weeks ago. My Ramp test then wasn’t a… complete success. I couldn’t maintain power at the top end, and ended up with a result of 250 FTP. I wasn’t too concerned, as I felt stronger, and was doing OK on the workouts, albeit with Thursdays always being a challenge due to fatigue (I’d cut down the duration of some Thursday workouts to ensure I could complete Saturday and Sunday)

So finished the first 4 weeks of Sustained Power Build, and ramp tested again: Result? 250 FTP.

I was… irked. at this, so decided to retest (2 days later) using the 8 minute test. Result? 250 FTP.

So… I’ve decided to update my FTP to 250, and carry on with Sustained Power Build.

What’s strange here is… As the weather in the UK has been getting warmer, I’ve been doing some outdoor rides at the weekends, and… I’m faster. I’m getting PRs on strata segments that I rode late last year, and this weekend I rode a segment that I ride regularly (I’ve done it > 150 times) and got a PR. Not just a PR, but the 5th fastest out of the 5000+ people that have ridden the segment on strava out of all time.

So… I’m clearly getting faster.

But my FTP test results would suggest the opposite.

So the question is:

What’s the best training strategy going forward?

Should I move from Mid-volume back to low volume?
Should I update my FTP to what the tests say?
Should I carry on with lower FTP at mid-volume, and build up again?
Should I add in more recovery time to the mid volume plan?

(My “A” race this year is the 100 mile Velo Birmingham on 12 May - so I’ve got 9 weeks to experiment)

did you do an FTP test outdoor? would be interesting to understand what is happening because, from how you tell it, could also be simple “demotivation” in indoor training\tests …

Maybe your trainer is out of calibration? I.e., it may read 250 W but in reality you are pushing say 280 W, or 290 W. Did you try a spindown (in case you use a Wahoo Kickr), or whatever else it may be called for other trainers?

Also make sure your drive train is in good condition (lubed chain). That could cost you some additional power.

I’m using Virtual Power on a completely traditional, non electronic trainer. (Tacx bluemotion) so equipment errors/calibration issues are out of the question.

It’s the legs, damnit.

Is your tire pressure and roller tension the same as before? You can significantly impact rolling resistance if those change and it will effect your dumb trainer virtual power.

sorry, so you don’t have a PM?
Virtual Power is sensitive to pressure and tire condition … as long as one of these parameters is different, from one training session to another, you have a very large FTP fluctuation
check the pressure, the tread condition and also the brake wire

Using virtual power, I’d be even more convinced it’s a “calibration” issue. In addition to tire pressure & roller tension that has already been mentioned, changing the actual tire can have a huge effect.
I had an issue once where the tire circumference setting in the app changed on it’s own. I went from crushing workouts to completely failing them overnight. It took me a week to figure out what was going on…

With virtual power I’d say equipment issues are even more likely, especially since you’re setting PR’s left and right

Good suggestions - I think tyre pressure is reasonably constant, but I’m not checking in that much detail. I think that could well be the source of the change.

Which also helps me answer my question: what should I do? Adjusting FTP down, unless I actually change tyre/tension, as that way I’m training against the same metrics as I’m testing against.

I had the same trainer (blue motion) 3 years ago and my wife bicycle had not PM
my advice is to always check the tire pressure, always adjust the “roller” knob in the same way (rest on the wheel, count the number of turns), always use the same brake setup and redo the FTP test with these parameters