KICKR Bike - Power Seems Lower - Anyone else with this experience? Should I manually update FTP?

I’m in the dead middle of a Short Power Build - Mid Volume Plan. FTP 239. Been using gravel bike + KICKR Core for duration of using TrainerRoad, but just picked up a used KICKR Bike V1 now.

Last week was supposed to be a recovery week (plan had 5x endurance workouts this week). However, they felt like sweet spot workouts when I switched over to the KICKR Bike. I was noticeably sore after my Sat 90min ‘endurance’ workout. I don’t have power meter pedals to compare, but I feel like the KICKR Bike might be 15-20w lower than my Core. KICKR Bike does not support calibration either and I don’t have power meter pedals to compare.

Question: Tomorrow, I start back on VO2 Max focused workouts (Taylor +2). Would you manually adjust FTP down now or just see how you do and adjust intensity mid-ride if you feel like it’s a beatdown?

Same basic rule applies: Whenever you swap an item in the power data chain, you should retest or reevaluate FTP. In this instance, you have changed two key variables:

  1. “Trainer” via the new Kickr Bike. There are notable differences in the drivetrain used here, related to gearing and flywheel setup. That is not a small difference IMO and likely to impact FTP test results even if you kept power data the same with something like power meter pedals (which are not part of the equation here anyway).

  2. Power data measurement is different. Despite all the tolerance claims, we see enough discrepancies to legitimately question the data from any device unless it is matched to well known sources.

Per both above, a proper power test is likely the “best” solution. You can sure swag it based on your recent experience, but with all that is at play here, a test seems like a good idea IMO.