Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

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marcinwoz
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Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by marcinwoz » Fri Jul 20, 2018 10:31 am

Hi

I was redirected to this forum when asking Zwift for help with the following issue:

What can I do to increase resistance on the flats when running Zwift controlling the Tacx Vortex (Ant+), and reading power from BePro pedals?

I am used to running ERG mode on my small front ring (36t). I can easily generate over 350 watts in the small ring.

When running Zwift in free mode, the resistance is 200 watts max on the small ring. I have to change to the big ring to generate more, but that increases the speed and generates more noise.

I know I can turn the knob on the Vortex to increase contact with the tire. But the impact of that is very small.

of course, the trainer difficulty slider does not work on flats/ negative slopes, so I doesn't help either.

any solutions?

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Alex Masalovich
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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by Alex Masalovich » Fri Jul 20, 2018 8:33 pm

Note the limitations of the Vortex operating range:

Image
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mcorn
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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by mcorn » Sat Jul 21, 2018 4:45 pm

I don't think I really understand why you think you have a problem. If you want more resistance from the brake in non-ERG mode, what you are really saying is you want to either increase road speed or go up a hill, so that is what you need to do, which means using a higher gear on the flats. You are already getting accurate power measurements independent of the brake, so that is not an issue. About the only other thing I can think of is to increase your body weight setting. It seems a little odd that you would not expect the noise level to increase if the wheel is turning faster.

As Alex points out the chart, the Vortex brake has some limitations in terms of the resistance it is capable of generating, but it sounds like you are capable of staying inside the curve if your increase your gearing by going to a higher chain ring.

marcinwoz
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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by marcinwoz » Mon Jul 23, 2018 9:51 am

mcorn wrote:
Sat Jul 21, 2018 4:45 pm
I don't think I really understand why you think you have a problem. If you want more resistance from the brake in non-ERG mode, what you are really saying is you want to either increase road speed or go up a hill, so that is what you need to do, which means using a higher gear on the flats.
I want more resistance at 0% gradients in Zwift. I know Vortex can do it - it can generate 300 W on ERG with 36 front/ 19 back gearing.

On Zwift, I have to put it all the way to 52/12 to generate 300 W on 0%. This requires much greater flywheel speed, vibration and noise. Why should I cope with that noise if I know the trainer doesn't need that much speed to generate resistance?

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Alex Masalovich
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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by Alex Masalovich » Mon Jul 23, 2018 12:15 pm

marcinwoz wrote:
Fri Jul 20, 2018 10:31 am
I was redirected to this forum when asking Zwift for help with the following issue:
marcinwoz wrote:
Mon Jul 23, 2018 9:51 am
I want more resistance at 0% gradients in Zwift.
Your desire can theoretically be realized if the wind force and wind direction settings are available. Contact the Zwift support team again.
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Alex Masalovich
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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by Alex Masalovich » Mon Jul 23, 2018 3:55 pm

Try also the following workaround:

1) Disconnect the Vortex from Zwift. Leave your power meter connected as a source of power data.

2) Connect the Vortex to the Tacx application on a smartphone or tablet: Tacx Training app or Tacx Cycling app. Choose the type of workout that allows you to achieve the desired power with the desired gear ratio and roller speed.
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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by mcorn » Mon Jul 23, 2018 8:14 pm

marcinwoz wrote:
Mon Jul 23, 2018 9:51 am

I want more resistance at 0% gradients in Zwift. I know Vortex can do it - it can generate 300 W on ERG with 36 front/ 19 back gearing.

On Zwift, I have to put it all the way to 52/12 to generate 300 W on 0%. This requires much greater flywheel speed, vibration and noise. Why should I cope with that noise if I know the trainer doesn't need that much speed to generate resistance?
While the brake can generate more resistance, it needs some kind of input signal to do so. The factors that cause the brake to generate more resistance are more speed, more slope, more weight, rough road surface, and as Alex suggests, more wind resistance. If you are not operating in ERG mode, you can't just turn up the resistance with a dial. Increasing the tension on the roller and tire pressure can also increase reported resistance on your power meter, but there is a limit to that and too much resistance on the roller can cause too much stress and wear on the brake itself.

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ms6073
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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by ms6073 » Mon Jul 23, 2018 9:25 pm

marcinwoz wrote:
Fri Jul 20, 2018 10:31 am
What can I do to increase resistance on the flats when running Zwift controlling the Tacx Vortex (Ant+), and reading power from BePro pedals?

How about stop riding on the flats? What would you do out on the open road in the real world? Final suggestion is to give Road Grand Tours a try as it is free and offers a pretty realistic virtual version of Mt. Ventoux which I guarantee has no flat terrain.
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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by mcorn » Tue Jul 24, 2018 7:08 pm

ms6073 wrote:
Mon Jul 23, 2018 9:25 pm
marcinwoz wrote:
Fri Jul 20, 2018 10:31 am
What can I do to increase resistance on the flats when running Zwift controlling the Tacx Vortex (Ant+), and reading power from BePro pedals?

How about stop riding on the flats? What would you do out on the open road in the real world? Final suggestion is to give Road Grand Tours a try as it is free and offers a pretty realistic virtual version of Mt. Ventoux which I guarantee has no flat terrain.
It's all kind of silly because, as you are suggesting, increasing resistance on the flats = a hill.

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Re: Zwift - low power on flats (Win7/Tacx Vortex/BePro/Ant+)

Post by ms6073 » Wed Jul 25, 2018 12:21 am

The best way to increase resistance while training on 'flat' terrain would be to use a Watt/Time workout in TTS or the Tacx Cycling App.
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