Power meter reading difference during FTP testing

I have been doing many ftp test utilizing the power meter in my hammer h2 on erg mode as well as resistance mode. However upon speaking to one of my close friends and ex coach he suggested for my to activate the power meter on the bike and test with that power meter instead. While my trainer road read an ftp of 287 the power meter suggested an ftp of 317 . While doing another workout after the test I did notice a 35-40 watt difference in between both, has anyone experienced the same reading output difference. (All power meter were re calibrated as well as spin down prior to testing)

Yes, power meter to smart trainer power data differences are more common than would be ideal. I am lucky that all my meters and trainers are within single-digit watts apart across a wide spectrum of power.

The best you can do is calibrate or zero offset each one as appropriate, and take what they give. The function of PowerMatch will take your power meter as the official data, and adjust your trainer to match (regardless of any differential between them). That way, you are using the same measuring stick (your power meter) as the one for all of your power data (inside and outside).

For reference, what is your exact power meter?

I currently have a Hammer H2 and on the bike I have a sram Dzero. I have been only utilizing the hammer power meter as the official to go to for measurements doing my workouts, should I continue this practice as it will ideally make me work harder with a deflated set of power values in order to sustainably develop a bigger curve.: thinking: grin:

As long as you pick one power source and use it for all TR workouts, your effort will be the same. The only differences are your FTP and thus the wattage targets of your workouts.

On the other hand if you use the Hammer FTP while using the Dzero for TR power, your workouts will be too easy. Likewise, if you use the Dzero FTP while using the Hammer for TR power, the workouts will be too hard.

I would recommend you use the Dzero power and powermatch. That way, your indoor numbers and outdoor numbers are both consistent and meaningful.

As for the massive difference in power numbers:

  • Double check all firmware has been updated.
  • Perform calibrations (DZero)
  • Perform spindown (Hammer)
  • Worst case, contact Hammer and/or SRAM/Quarq support,
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If you decide to use the DZero for your power data, you should just retest and get the appropriate FTP for that device.

Great, thank you for the feedback. Moving forward I will be utilizing the d zero ftp of 317 for my workouts as my previous Ftp 319 which became a bit challenging only due to the fact I had not taken a recovery week since September las year and I am still very actively performing strength training as this has been a staple practice for me through the years. I am positive the CTL of 127 heading into the season has not helped make things any smoother. I will have to monitor as I already started the short power build high volume. once again thank you for the feedback team .

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