Wahoo Speed & Cadence Sensor with Spin Bike

Hi there,

Will try and be brief.

I want to try out Zwift. I have a spin bike (flywheel is 9" radius, 18" diameter). Speed sensor mounted as close to centre as possible. Cadence sensor on crank arm of pedal.

I can’t commit to a smart trainer or power pedals as I don’t know if this is something I will take to long term. Quite an investment to find I don’t take to it.

So… what I’m wanting is to be somewhat accurate with my power to get a certain level of realism. Happy to turn resistance knob on spin bike to replicate hills.

But my spin bike, for example, reports 10kph. Wahoo app can be 20kph. Zwift with 20" wheel size can go 30kph+. This is simply far too inaccurate to get any sense of realism.

Anyone got any tips to get the most out of my current setup that I may be missing?


Unfortunately, there is no way for Zwift (or any app) to know how much resistance you have on the flywheel, so any power estimate is just a made-up number. The flywheel size is irrelevant and is not the same as actual wheel size.

If you have a heart rate monitor, there was an app that attempted to translate your HR into an estimate of power based on a baseline you set. Not very accurate but at least you will go faster on Zwift as your HR increases. Don’t remember the name of the app, though.

Without power meter pedals, I’m afraid that a dumb spin bike is likely to give you a very poor Zwift experience.

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Think you are referring to the hr2vp app

Seen some 2nd hand Favero Assimo Uno pedals for £275 … but thats more than my spin bike lol. Then the risk of buying second hand…

How poor would it be? Im ok with the manual resistance change. I’m ok with my overall speed being slightly slower than my real effort (as I still feel like I’m racing). Right now, I’d win every race without breaking sweat which is absolutely pointless.

Any tips to get my Zwift speed lower overall than my actual speed (without cranking up my resistance to ridiculous levels on flat)?

I think there are two types of realism you might be searching for:
Realism as to how far / fast you cycle on the Zwift flat compared to the real life road.
Realism as to how the difficulty pedalling changes when you go up (or down) a Zwift hill compared to real life on the road.

I don’t think there is much you can do on a spin bike to replicate the feel of hills.

However I think you can get better realism as to flat riding. You need to know how far you can cycle in 30 minutes on the flattest road you can find in real life ( or an hour or over whatever time your fitness allows) and how that feels on your body. Then once you get back inside on Zwift you need to make changes to your set up, spin bike resistance, Zwift wheel diameter etc, so that your 30 minute Zwift ride reports the same distance and feels as hard on your body. Ignore what the spin bike and Wahoo app reports it is the distance on Zwift for the 30 minutes you are aiming for. Choose the Fuego Flats on Zwift for these adjustment rides as this is flattest route around. Once you have set up as realistic as possible don’t change your spin bike resistance setting.

Once you have told Zwift you are on a dumb trainer don’t touch the spin bike resistance again. Zwift will take the appropriate action when you start to climb a Zwift hill. You won’t feel a resistance change you will still feel as if you are on the flat but Zwift will slow your speed down by amounts depending on the hill incline. As others around you on Zwift slow down on the hill so will you. (They will feel the hill you will not)

I think if you are tempted to change the resistance of the spin bike by making it harder so that you can feel the hill, peddle slower, get out of the saddle etc Zwift will not know that you have made that adjustment and you will find yourself being slowed by Zwift even further to an unrealistically slow speed.

I think if you start off by riding mostly flattish Zwift routes you might be ok and certainly get a feel for the Zwift experience.

If you like it you can then decide if you wish to spend more on Zwift controllable options for a far more realistic experience.

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This is probably the only way you can use a spin bike. Set it to one set resistance until you spin bike speed and real life speed match. But that will only work for flat road. Then you have to do it for every 1% increase in elevation and remember all the settings.

So in short as @MRBaldi_T-ZHR said it is not possible.

I installed stages poser cranks on my wife spinning bike and she likes it a lot.

Said so much better and shorter than my effort :wink:

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LOL, you have more detail. :slight_smile:

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Great advice - never even considered this logic. I guess that will be as accurate as anything for my setup.

I dont own a bike, not cycled since a kid (30 years ago) but found I’m getting sore knees from running. Wanted to keep up fitness and have some motivation, Zwift seems like a good fit when I read about these sensors to my existing spin bike.

Given my Zwift trial is due to expire in 2 days, I guess I could use my spin bike reader to judge the distance? Once I’m good to go, then load up Zwift and should be able to have a part experience?

So, in simple terms I should:

  • Keep the speed and cadence sensors on my spin bike (to communicate with Zwift). But completely ignore them (assume I set as 20" wheel so that I’m at least getting power watts down).
  • Turn up the resistance on my spin bike until I feel I’m riding at a similar pace as in real life (to counter the false power calcs from my sensors).
  • When faced with uphill, Zwift will slow me down anyway, but if I wanted I could up the resistance a bit to simulate a hill (knowing that I may be slower than those around me).

Then find I’m enjoying it and get the hunger for automatic resistance changes and buy a smart trainer :slight_smile:


Or pedal faster on hills if you want to work harder (not required)

TL;DR: Yes, but actually no.

The single most predictive factor in whether or not someone will continue to use Zwift is controllability. Even IF you put a power-meter pedal on your spin bike, the experience is just hollow. The vast majority will find it fun for a while and then just go back to watching Netflix or something.

While I’m empathetic of budget issues, TINSTAAFL. (there is no such thing as a free lunch)

If you want to Zwift like it’s meant to be used, ditch the spin bike, find “any bicycle that fits you,” and a used smart trainer. (used Tacx Flow Smart units are often available for a couple hundred Euros or USD)