Hi,
I’ve added Wahoo cadance and speed sensors to my non-smart spin bike on the IOS version of the app on my iPhone 13. The speed feeding to Strava from TrainerDay doesn’t reconcile with the speed on my bike - approx 50% higher from TrainerDay.
I note that the Wahoo app has the option of adjusting the wheel circumferance to calibrate the speed sensor. Can this be done in the TrainerDay app?
Thanks,
A speed sensor on a trainer bike makes no sense. If you are using ERG mode and put constantly e.g. 150W and you are on a small/easy gearing, Trainer resistance will be higher, than on a higher gearing. Because of that, speed of the wheel depends on gearing. And as I know, TD calculate virtual speed as you would driving on a flat good tarmac street outside, so it will differ what you see from your speed sensor and later in strava.
Sorry, didn‘t read that you have a non-smart bike. There the resistance is constant, and the power depends on gearing. So you can simulate with your gearing the „virtual slope“. So you can imagine, if you put same power output on a steep hill you are slower than you would be on the flat. It all depends on your gearing and the resistance of your trainer.
We don’t take speed from the speed sensor, we convert watts to speed. So in this case it is funny speed>watts>speed. So wheel size does not matter to our app.
As I am sure you are aware the speed of your wheel inside the house, maybe totally irrelevant to outdoor speed. Now with good fans inside if your heart rate is similar for speed indoor and outdoor that means your indoor speed is semi-accurate. In this case there is a problem with the virtual power curve you selected in our app. If you don’t care about power accuracy and only speed accuracy we have an adjustment you can do to lower your speed coming from our app.
But this will mostly affect higher speeds since it is drag coefficient. Getting the virtual power closer to accurate would be a more accurate method.
Thanks, that makes sense.
