Zwift/smart trainer/Power meter question….

So I’ve a smart trainer (wheel on) and a crank power meter…

I’ve only been using the smart trainer on zwift ( controllable and power) as I only had Bluetooth.

I’ve just got an ant+ USB thing…
Will I be better(more accurate) using the trainer for “control resistance” and the crank PM for the power on zwift?

Or is it much of a muchness?

Both figures are v similar..just half a second difference for zwift to react via pm it seems…

DrP

I would use the crank power meter for the power readings. Surprised that they are so close. My wheel on trainer was 10% higher than my smart trainer (which was a sad day as I went back to where I started – well not really but it felt like it!)

PM over wheel on trainer. Wheel on is way to hard to get proper repeatable accuracy.

As long as the two power sources read similar I wouldn’t have thought it mattered too much. I flip between Assioma pedals and Kickr for power source and never notice a difference.

Ah just noticed you have wheel on trainer, in that case definite go with PM for consistency.

Crank power meter.

Oh, and don’t forget, if it’s a LH PM only, you’re only allowed to pedal with your left leg in races.

PM over wheel on trainer. Wheel on is way to hard to get proper repeatable accuracy.

Very much this, I find tyre pressure has a pretty big influence on the power reading, for example – and in the garage the temperature’s not that stable which means the pressure varies quite a bit.

In a related qustion then, what are people doing about calibration ?

My turbo moves after every ride back to it’s place in the corner, I also wind off the pressure on the adjuster so teh wheel and tyre are not under compression.

Do people use just the Zwift calibration ?
Do people use say the Wahoo one?
Every time ?
Just when moving turbo ?

Or ?

What correlation do you actually get between the trainer and crank average power? I’m surprised the trainer can be accurate as the losses in the tyre are an uncontrollable variable.

I tested the implementation of the speed sensors in Zwift and the accuracy is horrible, like 80W steps between each power level, a rider can clearly get a big advantage just by riding at the lower end of the particular power steps.

My turbo moves after every ride back to it’s place in the corner, I also wind off the pressure on the adjuster so teh wheel and tyre are not under compression.

If you wind of the pressure how do you know you get it back to the same pressure if you aren’t calibrating each time? My wheel off trainer had a switch thing that took the pressure of but returned it to the same place so the only variable was the tyre pressure.

I do exactly that…. Wind it back to the same position each time.

I calibrate every time i do an ‘event’ so before the race tonight i calibrate, but not last night for example as that was just a social

Given its wheel off I suppose mines a bit different weeksy but I tend to do mine everytime I move the trainer or the bike, then as and when I remember if that’s a long gap.

In practice the elite trainer calibration is through their app rather than zwift (with no zwift option I can see) but as yet I’ve not had a different calibration number out of it so I doubt it needs doing often.

I calibrated my wheel on trainer using a mates crank pm a while ago….
Twiddle the ‘trainer map’ figures a bit..
But now I’ve got a crank pm (that, like I say, is pretty equal to the zwift reading) I’ll use that..
Also mine has a ‘click in’ bit to press against the tyre, so the same pressure each time….

DrP

Also… yeah.. left hand crank pm, so presumably there “some electronic magic” that provides a power reading when the right leg is working !?!?

DrP

Yeap. It multiplies by two 😄.

I only just dug my wheel on trainer out the cupboard for the first time in months the other night, it was still well within it’s calibration limits using the Tacx app. I may even look into joining you all on Zwift again soon.

Yeap. It multiplies by two

This makes the assumption I have just 2 legs…
What If i were in fact some sort of cycling octopi.. Can i set it to multiply by 8? There MUST be a way….

DrP