Which Tire Size Should I Pick?

I’ve successfully hooked up the speed and cadence Wahoo sensors to my spin bike so that it can power my avatar. But I don’t know which tire size to pick to match. The spin bike has a 19" flywheel so should I pick the smallest tire size in Zwift, which is 20"?

What type of spin bike do you have? How did you attache the speed sensor?

Zwift won’t work on a classic spin bike because it does not have a calculated power curve. so if it work the power numbers can be far from accurate.

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I’ve attached the cadence sensor to my shoe and that seems to be working accurately within ±2. The speed sensor is on the flywheel at the smallest/tightest part like it would be on a bike. I’m using a Peloton. I get that the power/wattage won’t be correct but I’m doing this for fun. No real racing. Just to see if I like biking in Zwift. I already love running in the world via my Treadmill. Figured since I have the peloton might as well see how far I can push it with that before spending money on a serious/intermediate trainer setup.

In that case you can pick any wheel size and any trainer. Just be sure it will be way off.

Hmm…that’s what I thought might happen. Oh well. Thank you for the responses.

Morning my first post,
It appears to me more and more people are looking to use such spin bikes, myself included. Surely if most spin bike users are using speed and cadence sensors then surely having a trainer setting for spin bike and selecting your flywheel diameter then Zwift having the necessary algorithm for this would be beneficial? And also attract more customers?


There a hundreds of types of exercise and spin bikes. Each one would be different. Most have a large number of resistance settings and I believe they would have a large difference in actual resistance based on wear. If a spin bike has standard bike pedal thread then you could buy a pedal based power meter and use that to provide power data to zwift.

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Also, on a bike + wheel-on trainer you can leave the trainer resistance lever at a constant setting and use gears on the bike to vary the resistance (higher gear -> rear wheel moves faster -> more resistance/power). On a spin bike your only option (apart from varying your cadence, of course) is changing the resistance setting which Zwift-compatible sensors can’t detect.