Different Tyres on Smart Trainer


I am using a Tacx Flow with my 700c Road bike. All works fine.

My daughter wants to use the same Turbo and her own account using a 26" bike with a smooth hybrid tyre.

I also want to swap my own tyres between 25-28mm.

Will they all work correctly with the smart trainer.


On the Zwift for iOS you can set the wheel size if you are just using a speed sensor, I am assuming that it will be coming to PC and Mac soon. 

Here’s a quick rundown of what this update includes:

  • Workout Adjustments : just tap the screen and use the FTP adjustment arrows to adjust workout intensity up or down by 10%. I’m happy to see this, because I’ve had many days where I just couldn’t hold the wattage I had set up–now I can reduce it a bit but still keep going, instead of skipping entire blocks.

Tire size selector

New tire size selector available if using a speed sensor. Great for kids or 650c wheels. Previously if your wheel was smaller than a standard 700c you were “cheating” since the Zwift assumed all speed sensor users were on 700c wheels. Now you may select your wheel size. This doesn’t apply to smart trainer and power meter users, of course.

  • Training Stress Score (TSS) is now calculated and shown after a workout. TSS is a popular metric used to track cumulative training stress. Created by the folks at Training Peaks, Zwift has received permission to use the TSS term in game. Learn more about TSS here >
  • Segment times are now always visible to help track your progress. I’m not sure what this means exactly, since I haven’t seen anything different in game yet.
  • Event duration and pace information displayed while waiting in an event paddock. A nice remember as you spin and wait for your ride to begin.
  • Trek Mission added : read details here >
  • Fixed crash related to Wahoo ANT dongle
  • Improved rider behavior to reduce “wild” riders
  • Stability improvements

As for just using a Smart trainer I don’t think the tire size makes that much of a difference as long as it is calibrated before hand.

That’s what I thought.

Just see conflicting info.

I would imagine that the speed is identical whatever the tyre size as it is the edge of the tyre moving over the roller that dictates the speed.

Was not sure about the width though.

Just remember the speed in Zwift is based on your watts, so that is why I don’t think the tire size makes a difference on a smart trainer. It is an issue when using just a speed sensor with a classic trainer and that’s why Zwift is implementing the drop down for tire siz