Different power outputs on trainers

Hi, I’ve been using Zwift for a couple of years now and done a fair few sessions. I was using a Tacx Flow and have just upgraded to an Elite Zumo. Having done my first session on the new trainer on the Harrogate course I am way off my Strava segment PB’s, so I was wondering if the change in the trainer would make a difference to the Strava segments based on the higher power rating of the unit so the steeper gradients are more realistically measured. Would that make sense?

Hi @Tim_Hogarth, welcome to the forums!

Going from a wheel on trainer to a direct drive will certainly give you a different power reading, usually the direct drive is far more accurate so you could see your numbers (FTP) go down or sometimes up. It makes perfect sense that it will be different.


Hi @Tim_Hogarth,

If I understand your question correctly, you are wondering if the longer segment times are a result of the new trainer having more breaking power and being able to simulate higher grades?

It depends:

-If this means that on the steep parts you are now grinding to a halt as your gears are not light enough, yes that would hurt your times.

-Assuming you can still keep a comfortable cadence by selecting lighter gears, there might be a small effect as the size of the flywheel and the higher breaking power will change the way you need to apply pressure to the pedals. But unlikely that this will cause a large difference.

-Most likely it is not related to the breaking power of trainers, but due to inaccuracies in the way they measure power. So the new trainer is probably measuring a lower power output, which is translated to lower speed.