Welcome to the club → My similiar problem
Here are some ideas:
- your FTP test was just a “bad leg day”. Repeat and see if it makes a difference.
- replace the power meter battery and retry, try a different trainer
- weight loss: if you are lighter in the summer, than in the winter, it’s also detrimental to power, as you can’t avoid losing some muscle. Walking to the fridge being overweight has advantages… On a bike being a few kgs lighter can be more beneficial than having a few watts more power. So you feel fitter, while being weaker
- if you do too much endurance Z2 training and neglect power, your power will suffer. You recover faster from your FTP test, but wont push as many watts. You can’t have both at top level. There is a visible difference between a 100m sprinter and a marathon runner.
The bottom line is, you want to get better over hills, be faster in a sprint, last longer on the ride. So the only important metric is really distance over time (vs. the other riders). Other metrics are there to help you figure out, how to improve distance over time. If your FTP is doing a nosedive like mine, but you end up being faster, then everything is fine.