Can't hit power targets in ERG mode workouts


I"m using a Tacx Flow Smart with a cheap MTB.

yesterday i wanted to do Jon’s mix workout. There’s some 10s intervals @ 400+ watts and i’ve noticed that my training didn’t have the time to adjust the resistance. at best i was at 230 watts or something.

for all other intervals (1-2mn) whatever the wattage was, i had no issue.

is there any reason? Is it just because my HT is a cheap one an 10s is too short to get the right wattage?

ps: i tried to keep the same cadence during the workout.

You should increase the cadence substantially when the power target increases. Pay more attention to the cadence number (i.e. the “Spin faster” message) and the power number will take care of itself (assuming you are using a smart trainer that controls resistance automatically).

Some more information about ERG mode in workouts in this Support Hub article.

Thank you for the link. I’ll read it. I thought during workout with ERG we were supposed to keep the same cadence.

Why would you do that and confuse the trainer when it’s already adjusting the resistance to the new power figure that Zwift has told it to use?

Because if you don’t increase your cadence substantially you just won’t be able to hit power targets for these very short intervals since it takes time for the trainer to ramp up the resistance.

It’s a different matter for longer intervals where there is time to let the trainer increase the resistance.

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Ok, it makes sense.

Isn’t that rather dependent on which trainer you have, and how quickly it changes resistance?

On a trainer that’s very slow to respond I can understand it. But on a more responsive trainer, increasing cadence is going to result in the trainer struggling to change the resistance to the required level due to the varying cadence.