TRAINER DIFFICULTY - naming change

Steepness reality setting

That would get confused with the Neo “road feel” setting.

“Halp! I’ve set Road Feel to max but I still can’t feel the cobbles!”

I think what they’re doing is taking your power and using that to calculate speed up the “real” gradient.

So let’s say you’re doing 200W and weigh 75kg, with trainer difficulty at halfway.

On the flat, you’d be doing 32kph.

On a 5% real gradient, you’d be doing 14kph.

On a 10% real gradient, you’d be doing 8kph.

But on the 5% simulated gradient, you’d be doing 8kph.

(Rough figures calculated using

So I reckon that in game your avatar would be riding at 8kph, even though you would be doing 14kph if it were really a 5% hill.

If your trainer difficulty were at 100% and you’re doing 200W, you’d still be riding at 8kph, but it would feel harder. The trade-off comes in the usual finding that it’s “easier” to push higher Watts up a hill than it is on the flat, and the steeper the hill, the more Watts people tend to be pushing. So at 100% you’d be more likely to be doing, say 250W - and that would propel you at around 9.5kph.

I’m guessing, of course, but it’s what I might do to ensure no one got “free speed” or any sort of advantage from changing the slope.

(Downhill is another matter - people who turn it off have an advantage over people who are going down a 10% gradient on a smart trainer, because the former can still push Watts while the latter spin out.)

Luckily for me, I’m not a game physics programmer, so I might be completely wrong about all this! :wink:

No matter the slope, everyone will find their own preferred gear range to ride based on their fitness. Unless of course they bought a bike with gears wildly out of their fitness range.

I don’t think Zwift does anything special. They just need your power number to calculate your speed.

But by adjusting the “trainer difficulty” you adjust the amount of torque that the trainer apply to resist movement.

So the formula for Power (w) is Torque * Speed (wheel speed)

So your wheel speed is determined by your gears and how fast you can pedal. So if you want more power you can do one of two things pedal faster or increase the torque.

You can see if you have close to 0 torque you wont be able to create a lot of power because your legs can go faster than 200rpm. Or you need crazy gear ratio.

But if you have a very high torque then you need very strong legs to pedal.

So somewhere in the equation is your sweet spot, that is why we have 7,8,9,10,12 gear systems on our bikes so we can hit that sweet spot.

So what is my point if you put the trainer difficulty to 0 you might not have enough torque applied to generate the 200W at 90rpm that you need to beat the other riders over the climb.

1 Like

Maybe name it “Sacrifice speed to ‘erase’ hills?” and have the range go from “I’m all in for this!” to “Count me out!”

Virtual range extension

what about “gradient feel”? 100% means you feel the gradient, 0 means you don’t, and 50% means you feel half the gradient.


Agree Dan - Gradient Feel

Llama explains it best here

Gradient feel sounds good b/c you lose the declines as well as the inclines when lowering the slider.

I was thinking something similar.

Along the lines of “Hill feeling”:

Flat ------------ Realistic

What is Trainer Difficulty anyways?

Gradient feel.

If the difficulty slider is going to be renamed, I would suggest either Isabelle or Roberto. :wink:

On a serious note, though, whether they rename it, or not, I would like to see some sort of actual indication of where you are on the slider. I’m tired of ‘I think I’m somewhere between 75% and 80%’.



Slidy McSlideFace.


+1 Gradient simulator

Trainer Torque limiter.


How about Gradient selector. With percentages on top of slider. Or like none, half and full

Don’t confuse implementation (controlling resistance with “gradient”) with the end result.

The end result is this is effectively a change to your gearing.

Bonus points if they want to denominate it in Gear Inches or Development.