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Difference at Watt Stages / Vortex 2160

Posted: Mon Jul 02, 2018 8:22 pm
by kanesaxo
Hello friends.

I've recently bought a Stages crankarm.

I've calibrated as should and went some rides outside. Yesteraday i thought to compare the wattage output through Stages App and wattage from 2160 Vortex connected with Tacx Cycling App (i haven't tried though with the on board 2160 computer).

There was a significant difference. Stages show 160 and Tacx Cycling App 200.

Any ideas ?

Re: Difference at Watt Stages / Vortex 2160

Posted: Mon Jul 02, 2018 10:39 pm
by Alex Masalovich
kanesaxo wrote:
Mon Jul 02, 2018 8:22 pm
I've recently bought a Stages crankarm.
For this power meter, the difference in strength between the right and left legs is important. See, for example, here:
https://www.bikeradar.com/forums/viewto ... t=13084882
kanesaxo wrote:
Mon Jul 02, 2018 8:22 pm
Stages show 160 and Tacx Cycling App 200.
left leg: 80
right leg: 120
Stages: 80*2=160
TCA: 80+120=200

Re: Difference at Watt Stages / Vortex 2160

Posted: Mon Jul 09, 2018 3:53 pm
by kanesaxo
It could have been that, BUT: i've ridden a friends bike which has Garmin Vector 3 pedals.

My left leg (like left crank of stages) is stronger than my right one. Almost 5%.

So to your example it could be 80X2 = 160, for Stages

To Trainer it should be 80 + 0.95X80 = 156...

Re: Difference at Watt Stages / Vortex 2160

Posted: Tue Jul 10, 2018 11:04 am
by Alex Masalovich
Vortex has a mechanism for adjusting the degree of pressing of the roller to the tire. Therefore, you have the ability to adjust the power output so that it matches the readings of your power meter.

Re: Difference at Watt Stages / Vortex 2160

Posted: Wed Jul 11, 2018 7:31 pm
by mcorn
Alex Masalovich wrote:
Tue Jul 10, 2018 11:04 am
Vortex has a mechanism for adjusting the degree of pressing of the roller to the tire. Therefore, you have the ability to adjust the power output so that it matches the readings of your power meter.

Changing tension affects the calibration of the brake, so if you recalibrate after changing tension, it really does not get you anywhere. But if you have a separate power meter, it really does not matter as you are not relying on the brake for power information supplied by the separate power sensor.

Re: Difference at Watt Stages / Vortex 2160

Posted: Fri Jul 13, 2018 7:14 pm
by Alex Masalovich
mcorn wrote:
Wed Jul 11, 2018 7:31 pm
Changing tension affects the calibration of the brake, so if you recalibrate after changing tension, it really does not get you anywhere.
Adjustment according to the power meter - this is the calibration, but in a different way. Is not it? Image

Re: Difference at Watt Stages / Vortex 2160

Posted: Fri Jul 13, 2018 8:01 pm
by mcorn
Alex Masalovich wrote:
Fri Jul 13, 2018 7:14 pm
mcorn wrote:
Wed Jul 11, 2018 7:31 pm
Changing tension affects the calibration of the brake, so if you recalibrate after changing tension, it really does not get you anywhere.
Adjustment according to the power meter - this is the calibration, but in a different way. Is not it? Image
Yes, I think you are correct. But you have to be sure not to run the calibration routine in the Tacx software if you do it that way. Running the calibration in the software would re-introduce the error you are trying to correct. Also, changing tire tension has to be done after the wheel is completely warmed up and tire pressure has to be maintained at the same level. Doing all of this is quite a bit of constant fiddling, which is why having an ANT+/BT power meter and using that as the source of power data for the software is the simplest and most accurate approach.