Wrong speed with wahoo spee sensor

Hello. It’s the first time I’m using zwift and it gave me wrong numbers. I’m using wahoo speed and cadence sensors of wahoo.
In wahoo app it tells me that I’m on somthing like 25 km/h and 80 cadence but in zwoft it shoes 15 and because of that thaw wattage is under 100 although I’m working very hard.
Can I do something for that?

You cannot compare the speed within Zwift to the speed it shows on the Wahoo app.

Speed within Zwift for a classic trainer like yours isn’t determined but the rear wheel speed and the power curve of the trainer and wheel size you selected on the pairing screen and that is converted to watts. With those watts, the height and weight you enter, ingame bike used, ingame drafting, ingame road surface and virtual elevation changes your ingame speed is determined.

Can you give use a more detailed rundown of your setup so we can better assist you.

Hey. thanks.
I’m using Tacx roller trainer.
I use speed and cadence sensor.
My weight is accurate and also my wheel size.
I think that there is no rise in the software settings.
After all of that, I think it gives me wrong numbers.
For exsample, Bike’s watt calculators tells me that 25 kph should be something like 200w but in zwift it’s 80-90…

Are you selecting the correct trainer on the Pairing screen?

On classic rollers you are just working against the rolling resistance of your rear wheel, whereas at higher speeds IRL and on Zwift most of your power will go to overcoming wind resistance.

It’s been ages since I’ve ridden on rollers with any meters, but I think your speedometer should probably be showing something like 50 km/h to get to anywhere near 200 W. Depends a lot on factors like your weight, tire pressure etc., of course.

It’s an unlisted rollers.
If I’m on 48/14 gear with 80 cadence. It should be something like 300-400 watt
and is shoes only 100…

Why would you think that should be 300-400 watts? The wattage would depend largely on the resistance. And with that gear and cadence i would think closer to 200 watts, if that.