Let’s cut right to the chase… yes, I opened up my Schwinn 220 and installed the Wahoo speed censor in the middle of the flywheel. Honestly, it’s seems pretty accurate so far, but I do have some questions.
So while I was riding on the California cicuit, my RPMs were perfectly accurate, my speed was accurate as long as the ground was flat, and my distance was within 10-15% of what my bike’s reading was. I’d say that’s an honest start!
However, my watts were registering at a consistence 380-400! I know that’s completely inaccurate, but I’m not quite understanding why I’m getting that reading. With the other data being quite accurate overall, why is it that my zPower and wattage is so dang high? I’d love to know more about this gauge and how I might be able to adjust this.
California Circuit???
Your watts (and in-game speed and distance) are off because Zwift does not have a power curve for that Schwinn.
For in-game speed using just a speed sensor: Zwift uses the wheel speed and the KNOWN power curve of the trainer and converts that to watts, with those watts, in-game bike used, in-game drafting, weight and height entered and virtual elevation changes your speed is determined.
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Thanks for the reply, Paul! I totally get that because I’m using an unknown trainer for my setup Zwift is lacking an accurate power curve, but it’s pretty dramatic. I’m peaking at 400 nearly the entire time that I’m peddling. Certainly between my Cadence, Speed and HR from my Apple Watch, the zPower should be adapting, right?
No, there needs to be a known power curve for it to be close to accurate. Speed, cadence and HR are not enough data.
Somehow zwift need to know how much power you are producing at a certain speed.
Your Schwinn 220 has 20 resistance settings, try putting it in the most difficult setting and ride zwift, you will notice it is very hard to get to 200w. If you have it in the easiest setting it will be effortless to get 400w.
This is why Zwift need a power curve to know what power is generated ant a certain flywheel speed.
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I wonder if Zwift will ever offer support for flywheel resistance. If at some point they do, then Spin bikes and other magnetic resistance bikes will at least be someone compatible given the ability to add the other censors in the right place. My 220 is unique because it has an open 4-spoke wheel and i can get the speed sensor right over the hub.
If there is a power - speed curve then it is possible. But without that it is not possible.
Yeah, I get ya. I wish there was a way to transmit the data that my 220 is gathering to Zwift… it’s all there.