Watts dropping

Hello everyone,

I joined Zwift a weeks ago and so far i am really enjoying it. I just noticed something a few days ago and would like to ask you about it.

Before Zwift I never used a Powermeter so I am new to riding based on Watts. I did a 60 min ride no intervalls and choose a very flat course. I was comfotavbly riding at 1,9-2,1 watts per kg and 75-80 RPM. After 35 minutes or so Zwift was showing me 1.7 watts per kg. I was still riding at 75-80 RPM and same gear not riding up a hill or coming down, 0% basically. Maybe there is some logic behind that which I just dont understand.

Using the Assioma Pedals as my Powersource.

Thanks in Advance :slight_smile:

What does your power output look like on the graph? Sudden drop at 35mins and hold steady there or did it slowly dip?

What trainer are you using? Could you repeat the same ride with trainer & pedals as power sources to compare the outputs? Send one to another device?

Have you tried ERG mode at your normal wattage to see if after 35mins you can no longer hit the same watts at the same cadence?

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If you are using a wheel-on fluid type trainer, as they warm up the resistance can change.


Thanks for the quick replies. I am using a basic wheel on trainier so Mikes answer can be the reason. I will definitly try the ERG Mode.

Thanks again :slight_smile:

A basic trainer wont have ERG mode.

I would agree with @Mike_Rowe_PBR. As the trainer warm-up the resistance will change.


Yes youre right just read about ERG mode. I just hang on then and hope the prices for Smart Trainers go down as they did last year here in Germany.

You could just shift to a different gear to keep your watts steady once they start dropping.

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