Virtualpower vs ERG

My wife has been using the low volume base plan for about a week after doing a ramp test. Currently she doesn’t have a smart trainer so it’s all based off virtual power. I’m getting a new smart trainer so I’m going to give her my old one. Would you recommend she does another ramp test and starts the plan all over or just continue where she’s at while using the smart trainer?


  • 100% Yes, retest FTP.

  • Anytime you change from one power measuring device (including swapping from Virtual Power to any other devices) you really should redo your FTP/Ramp Test. Despite claims of accuracy, most power measurement devices vary, and will give different results for test.

  • No need to restart the plan. Once she retests, she will have a new FTP based on the new device. Using that device and the related FTP should be very close to the same training effect as she moves forward through the existing plan.

  • There can be differences in perceived effort at power above or below FTP. This can happen when two devices (old VP to the new one in this case) have a different “power curve”. It’s possibly that the effort outside of FTP may well vary. So things like VO2 Max or Anearobic may feel easier or harder depending on the differences between the old and new devices.

  • I’d just plan to adjust to those efforts as is normally recommended. They may not even be evident, but I wanted to mention it because it does show up in some cases.


Just to echo what Chad had advised, once you have retested with power the training effect is very similar to the excellent Virtual Power.

What I did when I knew my power meter was en route was skip forward in my plan to a few days before my next scheduled Ramp Test, giving myself adequate recovery before the test, then returned to the previous point I was at in the plan with my new, much reduced, but accurate FTP.

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I always forget to suggest this in my initial reply on new power measurement devices. But it is very worthwhile to create “Seasons” that capture the time of the old device, and a new Season for the new device.

The potential differences in the devices can lead to lack of new power personal records if the old device measures higher than the new one (pretty common, especially with VP). So do create an old season and a new one.

Thanks everyone. This is exactly what I needed. Now she can suffer like the rest of us lol.