Set riders weight...heavier. Nonsense?

Hello everyone,
after months of studying, I finally decided to get myself a smart trainer and join the Zwift community, taking advantage of the lockdown going down here in Italy.
I got an entry level smart one, a Tacx Flow smart.

I like it, I’ve taken a few rides and enjoy it, but I still have to manage and solve a few questions and doubts about whether I can “optimize” my ride experience.

One thing in particular: I know my Tacx can handle jus a 6% gradient, but I cannot understand how it works…Let me try to explain myself with an example:
Let’s say I’m riding a 6% climb at 150watts.
Climb inclines up to 10%, and of course I don’t feel any change in resistance, so I keep riding at same power.
Here is my point: since my trainer can provide a max power of 800watts, is there a way to make me feel my climbs harder even above the 6%?

That leads to the title: what happens if I change my weight using a heavier one? I’m 72kilos now, if I set a heavier one would Zwift require more power to climb, leading to a harder feeling of the climb itself?

I’ve already set the trainer difficulty to 100%.

Oh and by the way, I think I would achieve my goal if we could set the difficulty up to 200% (like Tacx premium app), right?

Hope I had explained myself, maybe I said something really dumb…


If you increase weight Zwift will require more power to travel at the same speed as if you were lighter. I dont believe the trainer will react differently, trainers dont care how much you weigh, they only take the incline/decline info from Zwift and act accordingly.

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Uhm thanks Mike you got my point, and ok I guess now I better understand how it works…
Hence I guess that the possibility to set a 200% difficulty would end up to the same results…
I think that if I want more pain I’ll just have to lower my gear :sweat_smile:

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That is the way to do it if you want it harder and go faster on a hill then put the bike in the big front ring and small one at the back.

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Maybe I am missing something but I am coming from the place as Alberto: ie when gradient goes up surely the resistance applied by the smart turbo should go up to simulate the gradient.

One time that this doesn’t happen (I think) is if I am doing a workout with Erg mode on. This is a deliberate feature of Zwift/Erg mode I am sure.Most of my Zwift sessions are planned workouts with set intervals (eg 300W for 3 min then 180W for 3 min). It doesn’t seem to matter what the Zwift gradient is when I do these intervals, turbo resistance only changes if I am not hitting these targets. In other words it doesn’t really matter what Zwift course I am doing at the time- whether the Alpe or a flat Richmond route, the turbo resistance seems to be dictated how close I am to the workout interval target power and the gradient has no affect on how the turbo is reacting. The gradient will impact on my avatar’s speed, so if I am working at 180W and the gradient goes from 3 to 10% the speed drops but the turbo resistance is unchanged. My workouts come from Training Peaks and are uploaded to Zwift but I doubt that this makes any difference and would guess that a Zwift workout would work similarly when Erg mode is on.

However doing bunch rides and solo rides I am fairly sure my turbo resistance does change in response to gradient. Might be a bit harder to tell in a bunch ride as inevitably you will have to put out more power to hold the wheel of a lightweight whippet in front when the slope ramps up, however riding solo I would think the gradient change should be obvious if the turbo is responding correctly. I will try a solo ride later to check.

if anything, in your case setting difficulty to maximum is harming you not helping you

if you set it to the default, then you’d notice a change in resistance in grades up to 12% (with your 6% max grade trainer) and you’d have a more realistic experience rather than the difficulty being maxed out at low gradients.

try lowering the difficulty and see if that creates a better user experience on your trainer

What? Really?
I thought I was one of the few newbie that had understood the trainer difficulty settings :sweat_smile:.
When you say “default” you mean 50% right? I thought that on a 6% climb with the setting on default I would have felt like a 3%, and an actual 6% with the difficulty at 100%…what am I missing?

Read it again. :blush: You get less resistance send to your trainer, but you have a larger range of resistance change. If you exhaust your ~ 6% at 100%, the next 10% will just lower your speed in the game, you won’t notice a difference anymore yourself.

The easiest thing is to forget about elevation, because there is none. There is just a resistance amount that is send to your trainer. Zwift calculates that with the elevation profile of the route and your weight. Those are static properties of the activity. The dynamic property is the force you apply in reaction to those changes.

The resistance that has to be overcome depends on your choice of gear. There is nothing in Zwift that cannot be done at 50% in the big ring of a compact. You just shift less; that’s possibly an entertainment penalty.


Personally, I think he should just get a Kickr or Neo, instead! :laughing: :laughing: :laughing:

I have a NEO and ride at 50% since the front derailer broke. As I said, slight entertainment penalty. But then, up the Alpe, for example, I don’t shift at all, anyway.

What I learned from that is that what I really want now is not a new front derailer but the difficulty slider with labelled stop marks easily accessible in the companion app. No small ring, no cross chaining, less wear and tear, more sustainability.


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