I perform calibration on my smart trainer for all my workouts but have neglected to check my tire pressure consistently.
Imagine my horror when my tire guage measured an incredibly low 30PSI!
Am I screwed? Do my current measures mean anything? Did I really have FTP improvements?
Short answer: Nobody really can know without separate power data for reference.
Long answer: You may be perfectly fine, but it’s not possible to tell without a set of testing while using a power meter.
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The whole purpose of a spindown calibration is to adjust the power data provided by the trainer, and align it based upon the actual tire you have, the internal tire pressure, and the roller pressure against that same tire/pressure.
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Assuming the app and trainer have enough range in the spindown and related power data adjustments, you may be perfectly fine. But unless you confirm it with testing, or maybe contact the trainer maker directly, we can only guess.
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Who knows if they bothered to test with a pressure so low like that? It’s well out of what would likely be recommended from a tire or trainer maker. They typically recommend near max pressure for these applications, so I wouldn’t fault them for not diving down that far in their calibration setup and testing.
Unless you have access to an accurate power meter for cross-checking with the current state (low pressure), you just need to apply better practice as you go forward. I’d say setting tire pressure no less than once per week would be a good starting point.
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I would say that if you did work that felt hard (at least some of the time), you probably made some improvements.
Best thing to do would be to figure out what the appropriate value of tire pressure for your tire/trainer is, and then re-take a ramp test…actually take it, no AI FTP for this one. It might take a week or so for AT to get you dialed back in after that.
It’s entirely possible that the number that the ramp test spits out will be dramatically different than what you have now. It’s also possible that your trainer compensated perfectly for the low pressure. But you can rest easy that your fitness level didn’t change meaningfully from the day before you discovered the tire pressure issue, to the day after. Your numbers may be meaningless for comparison to anyone else or future/past activity. But your ability is your ability, and you’ll need to learn how to separate that from the number.
PS – The max pressure for my tire is 102 psi, so I pump it up to that, check it before each ride (my gauge causes very little air loss) and pump it up again if it’s 95 or below.
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Pumped tires + ramp test = FTP gains. Seems the calibration was enough to save me.
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