Power falling in ERG mode

Hi, not sure if this is a technical / software or physical issue. I’ve done Avalanche Spire last week and yesterday (repeating a week). Both times my power starts falling off in the later intervals despite the trainer being in ERG mode.

I thought that maybe my cadence is fluctuating too much? Tried concentrating during the last interval, but the power still wouldn’t go up.

I was extremely exhausted both yesterday and the time before, so maybe my pedaling gets erratic (i.e. one leg generates more power or smth)? Or could it be some technical issue?

Trainer - Wahoo Kickr Snap
Using a low gear - cadence ~90+, speed 17kmh

Has anyone experienced anything similar? Any insights?


maybe a combination of gearing and heat build up?


Looks like a power ceiling that’s going down as the trainer warms up. The statements “low gear” and “speed 17km/h” and the graph showing the problem increasing with time all support that hypothesis. First test I’d try would be shifting to a longer (harder) gear.


I agree.

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thanks! most seem to agree, will try a higher gear next workout

How did it go for you in the end @godzillla?

I’m seeing the same issue of subsequent intervals falling in power readings. The problem seems to affect higher power intervals more (like above 250 watt or so). Mt Goode for instance - similar to the Avalance you posted above power profiles.

Subjectively resistance is not falling by much and the training “feels” like a full training. But power ens up underreported by as much as 50 watts at later intervals.

My traier is Tacx Flux S though and this problem started recently.