Drop in FTP

Last year, I worked on my FTP and was able to get it up to 253. At the end of spring the power unit on my smart trainer died and I was sent a new unit. I installed the unit and calibrated everything. It was the start of the outdoor riding season, so I never really used it.

This year, all of my rides just felt a little sluggish compared to last year. I wasn’t putting out the power I thought I should be. I recalibrated everything and was still low. I’m not a really serious rider. I just like to keep in a little bit of shape, but it was bothering me some. Today I took a new FTP test and I was 184. I’m 90% sure it’s the new unit, but is there another reason I would drop that far? I’m in about the same shape.

If you feel like you’re at the same fitness level, it would be hard to envision a drop in power that large if the trainer is working properly. Do you have another source of power data or outdoor ride performance that would allow you to compare? Which trainer are you using?

Unfortunately, I do not have any other way of checking my power output. I have a tacx flow.

Wheel-on trainers are notoriously vulnerable to adjustment errors. I would start by double-checking the setup according to the manual, in terms of tire inflation, tension settings, and using a trainer tire.

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claimed accuracy for tacx flow is +/- 5% assuming it is set up and calibrated correctly (the sky’s the limit if not!)

if the power unit on the previous device “died” - there is a good chance it had an issue which would have affected it’s accuracy. did you calibrate the old unit before every ride? warm it up for 10mins before doing the calibration? (doing it ‘cold’ = won’t be accurate)

FTP of 253w is some serious wattage for someone who is “not a really serious rider” :smiley:

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All good points Ben. I was mostly looking for a sanity check. I calibrate about once a month, and I do it after a ride. I probably mostly need to recalibrate myself so I’m not disappointed by my (seeming) lack of output.

I ride about 50 to 80 miles a week over the winter. Less during the summer because I farm and just can’t seem to find the time during the busy seasons, so I’m not out trying to break records. I used to train for and ride century rides, but now they never seem to fit into the schedule.

For a sample size of one, having had a power meter via a turbo (Direto) since Dec '17 (aged 43 at time) and then a 4iiii crank meter since Apr '18, my estimated FTP from 95% of 20mins has been as low as ~195W to as high as ~298W. Currently ~254W while trying to find fitness again after Covid five months ago.

So a “baseline” of ~180W doesn’t sound too crazy, from that numbers comparison.