Spindown Power v. Riding

Okay, I’m not gonna include too many details because this is probably a dumb question so here goes.

Basic setup is a Kick Core controlled drive, running blue tooth through my phone "Android app).

I’ve done multiple spindowns on both the Wahoo app and Zwift. Very easy to hit 23mph. Third-highest gear, moderate effort, simple.

Riding on Zwift? Whoa buddy. Fan Flats sprint, dead-out I MIGHT be able to get to 28mph. That’s at around think 350 power. Even getting to 23 takes effort.

I’m assuming there is a simple explanation here and I’m missing something obvious but can’t figure it out for the life of me.


I would suggest first reading this:How Does Zwift Determine My Speed?

Hi Paul,

thanks. I’ve read it several times. But why is there such a difference between the effort on spindown speed compared to riding in Zwift? I would assume that formula holds for both, no?

I’ve looked a lot of places and read as much as I can, and was wondering if there is something simple I’m missgin - a setting or something. Because the difference in getting to 23mph on a spindown and getting there even on flat asphalt is massive.

I’m not incredibly strong by any means but that still wouldn’t explain the difference in those two situations.

Best Rgds

Spindown speed is literally just the speed your rear wheel is turning. The resistance level is low during the test because otherwise some riders would never be able to calibrate

Thanks, Ward.

Told you it was a dumb question :joy: