Understanding the Trainer Difficulty Slider


(Leon) #1

The Trainer Difficulty slider… The Voodoo setting…

Step 1.
FORGET GRADIENT.
For the purposes of this, completely ignore what Zwift officially say about this setting changing the gradient.

Step 2.
ITS ABOUT THE GEARING.
SLIDER @ 100% = YOUR ACTUAL GEARING

I will use my own setup as the example:
I am a TT’er and I use my TT bike on a Tacx Neo.
I race with 53/39 on the front and 11-23 on the rear.
I mirror this on the Tacx Neo with an 11-23 cassette.
(my FTP is 290, weight 87kg, w/kg 3.33)

As you can imagine for TT’ing, my setup works for me. However, when riding in Zwift, 39/23 is not the ideal gear ratio for the steeper gradients. Imagine using this gear outside for real on a really steep long climb…

This is where the Trainer Difficulty slider comes in.
100% on this slider for me would = my actual gears (53/39 11-23)
However, If I want to ride say the Epic KOM or Alp Du Zwift and I want to mimic a lower gearing setup of say 50/34 12-28 which would give me better climbing gearing and a better higher cadence during the climbs, then I would lower the difficulty slider to MIMIC SMALLER GEAR RATIOS

THIS is what the slider does, it allows you to alter your gearing to mimic smaller and smaller gear ratios.

I don’t know the ‘exact’ ratios it mimics as you adjust the slider downwards from 100% but this I would say, would be down to experimenting with finding a setting that gives you the cadence you require for the course you are riding.

SUMMARY
The Gradient is always the same (ignore zwift’s official wording if this helps), its your gearing that changes.

So, if your bike and trainer have the same cassette then 100% = your actual gears
Want to know what riding Alp du Zwift would be like on your real bike,with your actual gearing? use 100%
Have large gear ratios like my TT bike but want to do a hilly course with lots of climbing? - drop the slider down until you get a comfortable cadence on the steepest gradients in your lowest gear.


Zwift Hills not very realistic
Another Trainer Difficulty thread
(Lindsay) #2

Works for me.


(John) #3

Your explanation is exactly how I have interpreted the Difficulty slider, but you have expressed it more clearly, thanks.

I have thought of this slider simply as: Anything under 100% it like having additional lower gears available than the actual gears on your bike; and at the same time, not having access to the highest gear or two on your bike.

Everyone will land on a setting they feel comfortable with. As you suggest, there is no single universal right setting for everyone. I have set it at about 75%. I rarely have used the lowest gear, but it is good to know it is there!


(Gerrie Delport TeamODZ) #4

Nice write-up @Guyver1.

This is a good explanation. The “trainer difficulty” slider should have been called something different.

but be ready for those that will say that it need to be on 100% to be real, altho they have compact gears ie 50/54 12-34 on their training bikes.


(Joe) #5

But… but… there’s a tiny morsel of truth in here. I have two bikes I routinely use on my trainer. One is my road bike w/ 11-25t cassette, the other is my ‘cx/gravel/go anywhere’ that has a 12-36t cassette.

The bikes have different geometry and very different intended uses, and I swap cassettes on the trainer to match what I use on each bike IRL instead of changing trainer ‘difficulty’. Why?

If I’m training for a long, hilly gravel event, I’m just as interested in getting a feel for my power output while climbing @ given cadence in the different gear combinations that I actually have at my disposal IRL.

So, sure, watts = watts and I could use my road bike w/ trainer difficulty < 100% to spin better up Alpe du Zwift (instead of mashing up at 60 rpm) - and still build fitness… but I lose a bit of valuable ‘brain training’ in doing so.

OTOH, if I want to do some faster-paced riding or racing on flat or gently rolling terrain, the road bike is the ticket - not because I can’t ‘go fast’ on the 12-36, but because the 11-25 has smaller gaps between gears. I can’t do anything with trainer difficulty settings to make my cx bike gearing ‘feel’ more like my road bike’s tighter cluster.

Maybe I’m crazy (or just being difficult :D)… but I don’t mind the few minutes it takes to swap cassettes on my trainer.


(Shawn Minnich) #6

Very easy to understand explanation. Thank you! I wonder where most people keep the slider set.


(Joe) #7

You could start a poll.

I leave mine at 100%.


(Rob) #8

I am a totally new to Zwift, but my guess is that the slider on less than 100%
changes what the trainer sees, making the hill longer and less steep, such that at a constant power you will get to the top at the same time as on 100%.
The longer distance is then mapped (making it the ‘right’ shorter length) back to what it would be at ‘100%’; because that is what you see in the virtual world, distance and speed don’t change, but your gearing does.

I guess the way to test it would be to monitor your bike stats on a separate device, change the slider, and see what happens to the numbers on that. This should then tell you what the gearing ratio change is.