What’s the Best Zwift Trainer Difficulty Setting for Zwifters?

Ah, Trainer Difficulty. Simultaneously the most misunderstood and controversial setting in Zwift’s menu.

What it does is simple enough: Trainer Difficulty scales the gradients sent to your smart trainer. So if the slider is at 100%, your trainer is being sent the same gradient you see on the screen. If it’s at 50% (the default setting), your trainer is being sent 1/2 of the gradient you see on screen. So at 25% Trainer Difficulty on a 10% climb, Zwift is telling your trainer to replicate the resistance of a 2.5% climb.

Still confused how it works? Read Using the Trainer Difficulty Setting in Zwift

While explaining Trainer Difficulty to one Zwifter recently, I was asked what’s the best place to set Trainer Difficulty? And I realized that’s not a simple question to answer! So I will answer that question here, instead of burying it in a Facebook thread.

A Multifactorial Problem

There are several factors to consider when choosing your ideal Trainer Difficulty setting. I’ll discuss each below.

#1: Your Trainer

How much resistance can your trainer replicate? And does your trainer have problems with overheating on long climbs?

Higher-end direct-drive trainers can replicate gradients of 20% or more, but lower-priced smart trainers such as the popular Tacx Vortex Flow may only be capable of replicating the resistance of a 6-8% climb. If you set your Trainer Difficulty to 100% and your smart trainer can only replicate a 6% incline, that means the resistance you feel at 6% will be the same at 15%. Which isn’t ideal!

And this is a big reason why Zwift defaults to 50% Trainer Difficulty – because it allows even lower-end smart trainers to continue adding resistance as you hit steeper climbs, even if the trainer is capped at 6-8%.

Overheating is a problem we see in some trainers, even very popular ones. It happens when riding on long climbs at high Trainer Difficulty, which forces the trainer to work hard since applying the resistance break at low flywheel speeds takes a lot of mechanical force. If your trainer begins to malfunction on long, hard climbs, you’ve got two easily solutions: point a fan directly at the trainer’s flywheel to keep things cool, and/or reduce your Trainer Difficulty so the brake doesn’t have to work so hard.

#2: Your Weight

When is max incline not max incline?

The heavier you are, the more resistance your trainer must apply in order to replicate climbs. In fact (and this is a bit of a rabbit hole), most smart trainer companies use a 75kg rider when calculating their estimated maximum incline. If you’re a 100kg rider, your trainer can’t replicate the gradient listed in the specs – but if you’re a 60kg rider, it can actually replicate a higher gradient than specified.

So how should your weight affect your Trainer Difficulty setting? Just know that the heavier you are, the more resistance you’ll feel on the climbs. If you’re running out of gears and having to grind your way up hills, it’s probably time to lower your Trainer Difficulty so you can at least pedal at a cadence that doesn’t make your knees sore.

#3: Type of Route and Race

Are you racing on a flat route, or up a big climb? Is your race a TT, or a draft-enabled event?

It may seem odd, but many Zwift racers turn Trainer Difficulty up for flat races, and down for climbing races. Why? Because they want the gearing flexibility of low Trainer Difficulty on long climbs, while high Trainer Difficulty lets them “feel” slight changes in gradient on flat routes such as Fuego Flats.

High Trainer Difficulty on flat routes makes even more sense if you’re racing a time trial, because it lets you feel those false flats and apply a bit more power to keep your speed high. Without having your Trainer Difficulty set high on a flat route, you may be on a slight incline and not even notice the difference – until you realize your speed has dropped by 2kph!

#4: Outdoor Training Goals

Does your Zwift training replicate your outdoor target event(s)?

Many Zwifters train indoors for big events or races outdoors. That race may be a pan-flat criterium in Florida, or a massive multi-day Haute Route event in the Pyrenees. It wouldn’t make sense to set your Trainer Difficulty to 100% and attack major climbs in Watopia in order to prepare for the pan-flat crit. But it also wouldn’t make sense to ride flat routes or set your Trainer Difficulty to 20% if you’re training for massive climbing days!

Use Trainer Difficulty to replicate your event. If your event is flat, leave Trainer Difficulty low and enjoy that high-inertia feel of spinning along a flat road. But if it has a lot of climbing, you’ll want to keep Trainer Difficulty high, so you’re feeling similar gradients and riding at low inertia just like the outdoor climbs.

#5: Indoor Bike Gearing vs Outdoor

How does your indoor bike compare to your outdoor one?

Now that Zwift has been around for 5+ years, more and more Zwifters have a dedicated indoor bike as well as their outdoor bike(s). Often the gearing on the two bikes doesn’t match, (especially if you use an old ride for your Zwift bike like I do). Trainer Difficulty can help this, though! If you’re concerned about replicating the feel of particular climbs which you might be riding outside, you can use Trainer Difficulty to make your indoor bike’s cassette “narrower” or “wider” to match your outdoor bike’s gearing.

There’s probably a mathematician-physicist out there with a formula to figure this all out, but I would just do it by feel. Perhaps your indoor bike is an older rig with a 10-speed 11-25 racing cassette, but your outdoor bike has an 11-speed 11-32 for climbing. Assuming the climbs you’re choosing on Zwift mimic those you’re training for outside, simply reducing your Trainer Difficulty down to 75% or so should give you a similar feel as your 11-32 cassette would if you were using your outdoor bike on Zwift.

#6: Spinning Out on Descents

Do you need more to push against on the downhills?

Trainer Difficulty banter often ignores the fact that the setting affects the feel of downhills as well as uphills! If you’re spinning out on descents, reducing Trainer Difficulty and/or changing your gearing are the only fixes. (Well, that or just going slower…)

Little-known fact: Zwift only sends half the descent gradient to your trainer. So at 100% Trainer Difficulty on a 10% downhill, your trainer is replicating a 5% downhill. At 50% Trainer Difficulty, it’s replicating a 2.5% downhill.

#7: Lower for Draft-Enabled Racing

How much shifting can you handle?

I don’t have access to the stats, but my guess is the majority of Zwift racers run their Trainer Difficulty below 50% when racing. Why? Because it keeps their effort more even, reduces the need to shift gears, and ensures they won’t run out of gears on descents.

Some racers are purists (or perhaps are training for hard climbing races outdoors) and ride at 100% Trainer Difficulty. But more racers are pragmatic, and a lower Trainer Difficulty should generally result in a lower VI due to less resistance fluctuation. For many riders, this means the overall effort might feel easier at lower Trainer Difficulty since maintaining steady power is easier than doing intervals.

#8: Training for vEveresting

Training for the big one?

The official vEveresting rules state that you must complete your effort at 100% Trainer Difficulty on an electronically controlled smart trainer. So if you’re doing a vEveresting effort, or just training to do one… you’ll want that slider set all the way to the right.

What Do I Do?

So how do I handle my personal Trainer Difficulty setting? It generally stays around 30%, except when I’m doing a flat TT and remember to bump it up to 70-100%.

With these settings I never spin out on descents, I never run out of “easy gears”, and I can feel slight changes in gradient during TT races where it matters most. (I’m fortunate to ride a nice Wahoo KICKR in an air-conditioned space, so I don’t need to worry about overheating or maxing out the simulated gradient.)

Your Thoughts

What’s your Trainer Difficulty philosophy? Do you set it and forget it? Change it for racing on various routes? Share below!

Eric Schlange
Eric Schlangehttp://www.zwiftinsider.com
Eric runs Zwift Insider in his spare time when he isn't on the bike or managing various business interests. He lives in Northern California with his beautiful wife, two kids and dog. Follow on Strava

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Lottie
Lottie
3 years ago

Whatever you do, don’t change the resistance on a Elite Qubo Digital Smart B+. It can break the trainer entirely!!!!

Brian Kvedaras
Brian Kvedaras
3 years ago
Reply to  Lottie

What do you mean here Lottue, please explain because I have two trainers, his and hers…

Gonçalo Afonso
Gonçalo Afonso
3 years ago

Here we go

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Buddy
Buddy
3 years ago

BIG Thank You for putting this out again! I get it that people get annoyed with this topic but please remember that new or unsure Zwifters are trying to learn. Eric has now made it simple when the next person asks the dreaded trainer difficulty question… provide the link to this article and move on:) Ride On!

Chris
Chris
3 years ago

I have found a sweet spot at around 5% where the increase in resistance is sustainable when riding at threshold without having to change gear/cadence. The only downside I have found is on medium/steep gradient short bumps where people might push hard for a couple of seconds on higher difficulties and open a gap. Found it works well for team time trials.

Bogologo
Bogologo
3 years ago

very interesting post, thx Eric. I find some climbs become almost unridable at 100% difficulty as a light rider, like Radio Tower. I am a real climber outside and have no problem with 20% steep climbs outside. However, in Zwift at 100% difficultly in some steep sections, I almost can not spin at all, which I find annoying (Tacx Neo 2 (2018 Model))

Dan Connelly
3 years ago
Reply to  Bogologo

Many areas lack sustained climbs @ 13%. I have a 12-27 cassette on the Wahoo, and have three bikes I have used on the trainer, one with a 32 cog, one with a 34, the other with a 36. I always run 100% because I think the point of the game is to replicate outdoor riding. I like the challenge, I’m not so worried about race results, and like the feel of the gradient, but there that 36/27 gets me a bit bogged down on some climbs, even though I can handle pretty much everything in the SF Bay area… Read more »

Dan Connelly
3 years ago
Reply to  Dan Connelly

correction: I meant chainrings, not cogs, on the 32-34-36.

DCR
DCR
3 years ago
Reply to  Bogologo

One minor thing to be aware of, is that on a Tacx NEO series trainer, you’ll also want to ensure the weight defined in the Tacx smartphone app and then sent to the trainer is correct. Zwift won’t send that weight to the trainer, from a reaslim standpoint. And since the virtual flywheel on the NEO Series is 100% dependent on that weight setting, it can substantially impact realism.

Bogologo
Bogologo
3 years ago
Reply to  Eric Schlange

I will check this out as well, but do it after today’s race. thx for interesting answers

Pierre Baret
Pierre Baret
3 years ago
Reply to  Eric Schlange

This is the right explanation. I connected my Neo 2T with the Tacx smartphone’s application and it used a 75kg per default weight. My real weight is 63kg and Zwift had the information but didn’t communicate it to the Neo 2T => I had to change it with the Tacx app…

frank
frank
3 years ago
Reply to  Eric Schlange

I experimented about a year ago with my 1st gen Elite Direto and weight input using the Direto app definitely controlled what hill felt like

Anthony Goebel
Anthony Goebel
3 years ago
Reply to  DCR

I wish we could get 100% confirmation on this – per my comment on your review, both Garmin and Zwift have said it takes the weight from Zwift! I still don’t believe them (my poor partner may well be pushing my weight up hills…)

PS Am I really the only person that thinks 100% is the right thing to do? 🙂

Andrew Linquist
Andrew Linquist
3 years ago
Reply to  DCR

Ray, is that only a Tacx issue? I’ve got a first generation Elite Direto that’s shared by my wife and my 5 and 10 year old kids. I want to make sure the 5 year old isn’t getting the shaft. It’s hard enough for him to get that flywheel going. It’s sounds like it shouldn’t be an issue with my Kickr.

RHB
RHB(@robnfl)
3 years ago
Reply to  DCR

Thanks DCR. I just checked the Tacx utility app and sure enough the default body weight was set for 70kg and default bike weight at 10kg. I don’t know if I’ll notice a difference, but both of those are off by a couple of kg’s.

Bryan
Bryan
2 years ago
Reply to  RHB

Where is this setting in the app? I have a Tacx Genius.

sven
sven
3 years ago
Reply to  Bogologo

I find the opposite – I find Zwift gradients are slightly easier than IRL equivalent. My IRL setup is definitely heavier than my virtual Zwift bike, and I climb in a seated position

P Sauve
P Sauve
3 years ago
Reply to  sven

I see the same. In the real world I know I can do a steady and prolonged X mph at Y gradient. In Zwift at a given gradient, I’m struggling to match my real world speed.

Frank Drennan
Frank Drennan
3 years ago

Excellent article Eric. I like the idea of ‘scaling’ trainer max simulated gradient to the range of gradients in Zwift i.e. max. grad in zwift typically 15%. My trainer can simulate a range from 0 – 8%, so setting trainer difficulty around 50% means my trainer will vary the resistance “feel” over the full range on in-game grads. Turning it up on the flats to enhance feedback and stimulate more effort makes a lot of sense too. Finally, another trick to increase the restance ‘feel’ for those with a limited trainer is to drop a gear or two on a… Read more »

Stu McLaren
Stu McLaren
3 years ago

I’ve often thought over the years of dabbling with difficulty setting it would be easier for folks to understand if, instead of a bar slider, it was a cassette block which got bigger or smaller depending on how hard you want it… ok might be just as confusing for some, but the concept is easier to understand when considering the difficulty setting in reference to climbing hills. I came to this conclusion halfway up the Alpe and have climbed it at 75% ever since to match my cassette ratio.

Stu McLaren
Stu McLaren
3 years ago
Reply to  Eric Schlange

Fair enough, but that is almost a software issue isn’t it ?… anyway thanks for the explanation, I must have missed it above, I never appreciated the reduction in descending gradient, make sense now though when some are able to maintain higher w/kg and I’m spinning out… or maybe these folks are sitting at 110 rpm!

Renato Nardello
Renato Nardello(@renato-nardello)
2 years ago
Reply to  Eric Schlange

I think the cassette analogy is the right one uphill.

Toby
Toby
2 years ago

Cassette analogy isn’t right really as you need to change gear less with lower difficulty, at 0% not at all

Joe Pittman
Joe Pittman
3 years ago

Thanks for the article, Eric! I run my difficulty at 90%, because A) I aspire to some real-world climbing events (your item #4), and B) makes my Zwift setup’s 11-28 feel more like my real-world bike’s 11-34 cassette (your item #5).

Alex Fuller
Alex Fuller(@atfuller)
3 years ago

Great article. Important note: to officially vEverest, you need your trainer difficulty at 100%. After you do that, you’ll likely never set it to 100% again. Ever. For any reason.

Cédric Liénart
Cédric Liénart
3 years ago
Reply to  Alex Fuller

I agree 100% ! Having ridden on Zwift for years on the default 50% setting, I was shocked when I switched it to 100% :-O

John P.
John P.
3 years ago

I’m a 100 kg rider, and the bike I use on my Kickr SNAP and Zwift is an old (mid-1990s) Trek 520 touring bike. I do mostly group rides in the 2.5 Wk/g range, workouts and the occasional race as a workout, like to rotate through all the different Zwift lands/courses. For the first 3 years I left TD at the default 50% – I don’t really want to do a lot of shifting outside of the real killer climbs and I’m not worried about racing. However, doing so meant I was on the big ring up front and the… Read more »

Tord
Tord
3 years ago

I also use 20-30% during non-flat races, and the main reason is that I can stay on the large chainring all the time. One would imagine that 0% would minimize the need for changing gears, but it’s actually the opposite, at least for races on rolling terrain (think NY): since everyone push harder on uphills, you need to put in a bigger gear as soon as it tilts up, and a lower gear as it flattens out. With 20%, you hardly need to shift gear at all. About the overheating issue: shouldn’t the heat produced by the trainer be equal… Read more »

Mr Julian Bosley
Mr Julian Bosley
3 years ago
Reply to  Tord

Yes, the power output as heat in the resistance unit will be equal. However many trainers incorporate fans which cool the resistance unit, and the fan runs relatively slowly when training at high resistance and low soeed, hence the cooling effect is reduced and the resistance unit runs hotter.

Jörg
Jörg
3 years ago

Another thing to consider: if you have a kickr climb or kickr bike, it goes up and down according to the gradient sent by zwift. So if you want the rollercoaster feel in the esses or Titan’s grove or feel the steepness of the Alpe, you have to use 100% trainer difficulty.

Colin Peerman
Colin Peerman
3 years ago
Reply to  Jörg

or use the well-known hack of doubling your wheelbase length in the Wahoo App, which then means you get the same effect and can leave your trainer @ 50%

Jörg
Jörg
3 years ago
Reply to  Colin Peerman

Interesting, but I believe that hack won’t work with the kickr bike.

sven
sven
3 years ago

My trainer goes to 11 !!

I ride at 100% because I like to feel the terrain that Zwift has put so much time into creating – the changing gears, different cadences, sitting, standing helps keep me far more engaged during my rides.
I run an 11-28 on my trainer and 11-32 IRL – I find that the Zwift gradients slightly easier than the equivalent IRL. (my IRL bike is definitely heavier than my Tron!)

Mr Richard Neil
Mr Richard Neil(@richardneil)
3 years ago

The main reason I reduce trainer difficulty when racing especially on rolling courses is to reduce the need to shift gears. Zwift races are so intense that even shifting gears a couple of times reduces the power = getting dropped. Yes they can be be that tough – yet another reason why Zwift racing is not like IRL 🙂

Cade
Cade(@caderiver)
3 years ago

I usually run a 75% difficulty on my old Saris CycleOps trainer regardless of what kind of riding I’m doing. It makes climbing feel a little more real but the trainer doesn’t get bogged down and I’m still able to spin a little on climbs like the radio tower.

Paul Rayner
Paul Rayner(@paulrayner)
3 years ago

I feel that instead of Trainer Difficulty, “Trainer Realism” or “Gearing Realism” would be a better name.

I think this because, at 100%, your trainer replicates as close to a real experience as it can.

Also at 100% it’s as if you only have the gears on your real bike to help you, whereas at 0% it’s as if you have an automatic gearbox with an infinitely large set of gears.

Have I got it right?

Vasily K
Vasily K
3 years ago

I used to be riding on the maximum difficulty but now I noticed kind of struggle from gear search in some uphill conditions. And I also noticed recently a fact that after at least 80 km of riding my wahoo kickr 2018 gets a kind of vibration which is noticeable and annoying and you can do nothing but fix it along with complete disassembly and assembly the trainer. I suspect it’s a matter of overheating of the right bearing of freewheel. Sometimes it works silently for 1k km, sometimes for just a ride. But since I’ve started racing from home,… Read more »

sven
sven
3 years ago
Reply to  Vasily K

have you contacted Wahoo support? – I have found them to be very good

Vasily K
Vasily K
3 years ago
Reply to  sven

Yes I have. But my warranty period has finished. I live in Russia Moscow and it’s impossibe to send the box of 25kg to them and then back as well.

rdcyclist
rdcyclist(@rdcyclist)
3 years ago
Reply to  Vasily K

Have you done a factory spindown? That fixed the vibration in mine.

Vasily K.
Vasily K.
3 years ago
Reply to  rdcyclist

I haven’t. Could you expand on that one, how to do it?

dan
dan
3 years ago
Reply to  Vasily K.

with the App

Adrian Amos
Adrian Amos(@ahamos)
3 years ago

I reduce trainer difficulty to reduce the wear on shifty bits. There’s a little bit of shifting to get up to speed, but then only rarely am I shifting during an event. I keep it at around 25% because I actually found I shifted MORE at 0, but I was more successful at racing when it was at 100%. YMMV.

K4m1k4z3
K4m1k4z3(@vitek-holubovsky)
3 years ago

0% and 12-25 cassette for me. I prefer to have maximum control over my power output and cadence.

Steven Bannell
Steven Bannell
3 years ago

If I reduced my difficulty to 50% and climb Alpe du Zwift for example, although it reduces the gradient to half, and I climb on my big ring, doesn’t the total amount of watts required to complete the climb stay the same as if it were 100% on a smaller ring?

Mr Julian Bosley
Mr Julian Bosley
3 years ago
Reply to  Steven Bannell

It does indeed

Oleg
Oleg
3 years ago

I am unfortunately still confused.

Ever since I started with Zwift 5 months ago, I’ve had it set at 100% difficulty. I also use a fairly cheap smart trainer – the Tacx Vortex Flow in fact, and so it probably has a Mac 8% gradient.

I do a lot of Alpe runs.

So when the gradient in Watopia is showing 11%, and it’s trying to send 11% to my trainer (but it can presumably only handle 8%), am I cheating the system?

Because I like my 100% difficulty setting, but I definitely don’t want to be misrepresenting my performance.

Paul Rayner
Paul Rayner(@paulrayner)
3 years ago
Reply to  Oleg

It’ll feel like 8%, but you’ll still need to produce enough power to climb an 11% climb.
So it’s the same as climbing an 11% climb in a lower gear, i.e. not cheating.

Puppy Lander
Puppy Lander
2 years ago
Reply to  Oleg

It’s not cheating.

The analogy is more like people who don’t have smart trainers. They’re not feeling automatic resistance.

The computer will “slow” these riders “virtually”. But they can make up for it by shifting into a harder gear.

These riders still have to do X Joules of work to complete a climb. And if they want to do it within a certain time,

X Joules / Y seconds = X/Y Joules per second = X/Y watts

Power requirements remain the same.

chris benten
chris benten(@chris-benten)
3 years ago

My H3 overheated on the tower climb when at 100%, standing 40-50 rpm @ 250 watts…so now I do ~50% (in the middle but no scale so…) just to get some extra low end gearing. I am 103 kg, nearing 60 and climb like an anchor.

Mike
Mike
3 years ago

Another great and thought provoking article Eric.
So how does Zwift handle dumb and non- interactive trainers, is the gradient effect set at the Zwift default or 100%?
Thanks
Mike

Puppy Lander
Puppy Lander
2 years ago
Reply to  Mike

Zwift “slows” these riders “virtually”. But they can make up for it by shifting into a harder gear.

These riders still have to do X Joules of work to complete a climb.

Say the climb takes 1000 Joules.

If they want to do it within 10 seconds, that’s….

1000 Joules / 10 seconds =

1000/10 J/s =

100 J/s =

100 watts

In other words to do the work (complete any given segment) in the same amount of time, the power requirement must be the same.

DAVID LEWINGTON
DAVID LEWINGTON
3 years ago

I will have to review my trainer settings when I resume Zwift in November. I have a Tacx Vortex trainer and have found that the climbs on Zwift are much harder than real life. My bike club friends, who use various other trainers, have said the same thing. If its possible to dial in realistic feel using settings I would find the various routes more enjoyable.

Keith
Keith
3 years ago

As an avid mountain biker, I like to spend my summers as much as possible out on the trails exploring big mountains. Where I live is miles away from the big mountains in the UK and with a young family, I don’t have so much time to dedicate to Mountain Biking as I would like. To that end, I need to make sure that when I do get a rare weekend away, I need to be dialled in fitness to make sure I have the energy to not blow up after huge climbs. I set my trainer to 100% difficulty… Read more »

Graham de la Mare
Graham de la Mare
3 years ago

I’ve always set my Neo 2 to 100% to mimic the real world, but as others have stated, it might be a little harder on Zwift in relation to real world. I’ve been racing with slider set at 100 for nearly three years. I think I will now need to adjust it to get that sweet spot for particular courses (hilly vs flat). Also interesting about the weight and adjusting in the app. Great article yet again.

James Malone
James Malone
3 years ago

Thank you For this article! In 2017 when I started zwifting I always kept my trainer on 100% And I did have overheating problems and did put a fan on it. This year in 2020 I started using training peaks and all the workouts are a specific power outage and I find it very difficult to use zwift at 100%. And I now have it set at 0% and am enjoying it.

Dan Kapsak
Dan Kapsak
3 years ago

I’ve been trying to reset the difficulty, but the display on my Mac or iPad won’t show difficulty. how do I uncover it?

Martin
Martin
3 years ago

Can we have an article on no flat course resistance with kickr via Bluetooth? Getting sick of riding in 52 11 gearing at 90rpm and 150 watts means cannot race ever and stuck at 2w/kg group rides.

Paul
Paul
3 years ago

Tongue in cheek answer is that it’s how much of the £1000 you spent on a trainer is actually being used!

At 0%, you have wasted your money and might as well be sat on the cheapest dumb trainer you can find 😉
At 100%, you are feeling everything that Neo or Kickr can throw at you

John Beevers
John Beevers
3 years ago

Isn’t it a bit dishonest to transfer rides to Strava (leader boards) without quoting difficulty level.

Mudshark
Mudshark
2 years ago
Reply to  John Beevers

Why?

Terry
Terry
2 years ago
Reply to  John Beevers

Same power output regardless of setting

Frank
Frank
3 years ago

I like riding at 100% so it feels as much as possible like outside. Only for the long climbs (Ven-top and Alpe du Zwift) and the steep radio tower I bring it back just to have enough gears. No need to hurt my knees when it’s not really neccesary.

fritz westphal
fritz westphal
3 years ago

If I understand correctly, 50% TD equals half the gradient. So at the same power output I should climb a hill faster at 50% TD than at 100% TD, yes? Hope is that fair in a race if someone is riding 100%TD or 10% TD?

Bob
Bob(@stephenrellis)
3 years ago
Reply to  fritz westphal

No. All else being equal, your speed depends solely on the watts you deliver to the pedals. Trainer resistance does not affect the watts you deliver.

Bob
Bob(@stephenrellis)
3 years ago
Reply to  Bob

Shane Miller has a video showing this on YouTube:
https://www.youtube.com/watch?v=_mjAZyhOlt0
“The Zwift Trainer Difficulty put to the test up Watopia Wall – Same watts, same conditions, one lap with the setting at 100%, the next at 0%. Does it have any impact on my in-game speed?” — the answer is “No.”

Fabrice
Fabrice
2 years ago
Reply to  Bob

The video is quite obvious, the selector affects the cadence! If I’m right he uses the same gear or equivalent. At 100% his cadence is about 70rpm vs 85rpm for 0%, so it is really not the same effort! For the same value in watts, the higher cadence there allows to reduce the force of 18% to apply on the pedals… so it is huge 🙁 watt is watt but this depends on your cadence, higher cadence will be always easier and efficient than low cadence, it is mathematical and physical. do a repetition with selector at 100% it is… Read more »

Puppy Lander
Puppy Lander
2 years ago
Reply to  fritz westphal

You can define a hill by the total work needed to get to the top. Work = Force x Distance So you can have two hills that require the same amount of work to get to the top. Hill A takes 100J = 10N x 10m Hill B takes 100J = 5N x 20m The difference is, you have to fight 10N on Hill A, but only 5N on Hill B. All of that seems silly and irrelevant, but hold the thought because here’s where the magic happens… Power is rate of work. Watts is Joules per second. 100w =… Read more »

Louise somerville
Louise somerville
3 years ago

I usually run at 50% but i have four tough badges to get – my trainer only run at 6% so i have read somewhere that it is ok to drop below 50% because for me i get wiped after 4 hours on zwift

The Hook
The Hook
3 years ago

I may be a complete imbecile or I just don’t know what I’m doing! But why? Why have they implemented this feature at all? IRL I can’t go like, OK here comes a “nice” climb with 10% gradient, let’s see where’s the bottom so I can level out the climb to 5% oh 😮 it’s not there s*** now I’m going to run out of gears. On my first trainer, Tacx Neo T2800 I had at 100% and the same goes for my Kickr Bike. I had/have both trainers replicating my Roadbikes gears ⚙️ I did the 10K vEveresting on… Read more »

sarah
3 years ago
Reply to  The Hook

But on a real hill you can get off and walk…

Bill Nowlin
Bill Nowlin
3 years ago

Wait. What? Zwift gets around an overheating problem by reducing the virtual gradient? What? I studied physics a long time ago, and maybe things have changed, but I don’t think so. Every watt a rider produces on a “smart trainer” is turned into heat by the motor or electromagnetic brake resisting the spinning parts. Watts are watts. The same reason we can climb by “mashing” or by “spinning” at about the same speed is because we make the same watts in either case. Likewise, the trainer has to dissipate the same watts in either case. (Note: if the spinning parts… Read more »

Chris G
Chris G
3 years ago
Reply to  Bill Nowlin

The Aha moment… The faster a body loses heat, the more power you need to put into it to keep the same temperature… On many trainers this cooling is linked to the rotation of the disk/drum so the faster this rotates, the better it will be cooled, hence high resistance => lower speed of rotation => less cooling => hotter

ShakeNBakeUK
ShakeNBakeUK(@bakeuk_2)
3 years ago

20-30% seems to be the sweet spot for racing. Have to change gear every now and then, lets you feel the resistance on climbs so you know when to go hard, but don’t waste loads of power on multiple gear changes on tiny slopes.

Ron
Ron
3 years ago

I’m one of those “purists” you mention. Although the power can remain the same on uphills regardless of trainer difficulty setting, I’ve noticed that gradients never match with the muscle memory I have of riding a “true gradient”. My gut feeling has always been that the bio-mechanics, and particularly the muscle firing patterns must be different when the inertia is very low on the steep ascents; I remember my old, steep hill climbs and fully engaging for 360 degrees on the pedal stroke and I remember emphasizing more on the pullup. On long steep climbs, this would lead to considerable… Read more »

VanMich
VanMich
3 years ago
Reply to  Ron

Nice comment, For that upward movement much stronger IRL (climbing steeps even more), maybe it’s just a natural “balance move” we naturally do to help keep the bike reasonnably straight, as the arms may become unsufficient on the highest gradients where the forward leg pushes all it can ? So in order to help reduce the side movement as well as the forward, to help the upper body to stay straight and the rear wheel’s grip…. I may be way off !! Or maybe it’s a bike incline thing, maybe with the “Kikr Climb” (or just books under the front… Read more »

mark jones
mark jones
3 years ago

And for people using wheel-on trainers like myself I would advise lowering the difficulty on long climbs. I’ve had several trainer tires (Tacx and Vittoria) overheat and fail – they became lumpy and distorted, the Vittoria actually split and deflated – during my Tron challenge. The surface of the trainer roller can get rather hot and so can the tire. 100psi was adhered to.

Ludva
Ludva
3 years ago

Hello guys, just a quick question about the feel of little lumps on the road while riding on Zwift. It seems to me the resistance changes pretty dramatically even though the incline goes for example only from 0% to 2%. Trainer difficuilty is on default. Does anybody experience the same sensation?

Darren
Darren
3 years ago
Reply to  Ludva

I do and it’s the most annoying and unrealistic aspect of Zwift. I can be travelling at 25 mph on the flat, spinning at 95+ RPM an then hit a short incline of 4% and instantly be struggling to turn the pedals even though my avatar is reportedly still traveling at 20+mph. Paris is a typical example. The only way I’ve found to make it more realistic is to drop the TD, which is not ideal as I’d rather have the full gradient experience.
i just need the transition between gradients to factor in my current speed.

calayanrail
calayanrail(@calayanrail)
3 years ago

My outdoor bike is 50-34/11-32, and my indoor one is 50/11-28, so I simply set to 60% as (34/32)/(50/28) is 59.5%.

Mitchell
Mitchell(@rmpearce1964)
3 years ago

My two outdoor bikes have 11-28 and 11-32 gearing. My Wahoo has 11-25 cassette. I have picked 60% and just leave it there. Gradients of 12%+ feel every bit as difficult as outdoor gradients at that setting for me.

Alistair
Alistair
3 years ago

But if Zwift is scaling the grades (sending 2% instead of 4% or 8%), wouldn’t it make sense to always race at 0 on the slider? Why would a racer ever want to climb steeper than needed? Training is a whole different issue.

Puppy Lander
Puppy Lander
2 years ago
Reply to  Alistair

The hill is still there. In its essence, a climb is just a pile of work to be done.

Remember the work equation.

Work = Force x Distance

If the in-game hill is defined as

100J = 10N x 10m

Then a 50% trainer difficulty is

100J = 5N x 20m

And if you dial trainer difficulty down to 0…

100J = 1N x 100m

Zero grade but now you have to cover 100m in the time it takes someone else to cover a steep 10m.

Nathan Lipke
Nathan Lipke(@nlipke)
3 years ago

One new thing to consider. When riding with a pace partner with any hills you need to have your resistance set to 50% or less or else you’ll be yo-yoing off the front and back.

Matthew newell
Matthew newell
2 years ago
Reply to  Nathan Lipke

Oh thanks for that Nathan. Never occurred to me that was my problem with the pace partners. I will change it back down and see if that makes pacing B and A a bit more palatable

Al Little
Al Little
3 years ago

I find that as a heavy rider I spin out on races trying to get high watts, due to the resistance running out. to achieve a decent W/KG I need to do a whole race at nearly 105rpm, is there a solution to this? (I’m 100kg)

Tom
Tom
2 years ago
Reply to  Al Little

Just posted about the same issue above without seeing this. Did you figure anything out may I ask?

Steve Soll
Steve Soll
3 years ago

The trainer difficulty setting on my settings disappeared and now I can’t set my Climb. How do I find it and reset. I had it before on one of my Snaps but when I bought a new second snap, the setting is not there. Thanks.

Renato Nardello
Renato Nardello(@renato-nardello)
2 years ago

If I wanted to check what TD I used for a specific ride, where do I find that info?
Txs

Tom
Tom
2 years ago

I’m having some issues with my new (second hand) Elite Direto, in that I spin out on sprints – get up to about 120rpm / 800ish Watts and there’s no resistance left, even though I have more in my legs… Does anyone know how I can get a bit more top end? Not sure if the key is in the trainer difficulty setting or in something to do with the Direto calibration (calibrated v recently and accurately)? Does my weight setting in the my etraining app affect anything perhaps? Don’t feel like I should be spinning out like that –… Read more »

Marc Pujol
Marc Pujol
2 years ago

I don’t understand why there is such a complex non answer to what the Trainer Difficulty setting actually does. The question is if I climb a 10% grade over a mile do I wind up at the same place having exerted the same overall amount of power? My suspicion is the setting changes the distance calculation per revolution of the wheel (disc) changing the gear inch calculation. It would be like changing the final drive ratio calculation as if selecting (imaginary) wheel size from a wide range by just moving the slider. Yes, I know there is not a 672C… Read more »

robertpaulson
robertpaulson
10 months ago
Reply to  Eric Schlange

Is that entirely correct? There is also a speed element sent to the trainer 5mph on the flat is less resistance than 40mph – this is clearly not being changed with the setting at 0%, therefore its not just scaling gradient changes but the entire zwift resistance model? Is there a default resistance sent to a trainer at 0%? Is that fixed or impacted by weight entered in zwift? Does it vary across trainers? The reason I ask (if you ever see such an old comment), its super easy to detect main in the middle trainer cheats this way, nobody… Read more »

Puppy Lander
Puppy Lander
2 years ago
Reply to  Marc Pujol

“Does the Trainer Difficulty slider effectively change the final drive ratio (gear inch) calculation?” It must change in the sense that any setting other than 100% is an alteration to the physical gearing on your bike. (Minor quibble but, changing the gear inch or wheel size is the same as changing the cassette or shifting gears. The turn of the crank yields a different wheel rotation.) Trainer differs by affecting only one component of force: grade. Meanwhile, drive ratio applies to the summed force components.) Power = Force x Velocity But Force in that equation is the total of several… Read more »

Steven Tilly
Steven Tilly
2 years ago

Why change it back on a flat TT? At zero it makes everything feel flat. On a flat TT, week everything IS flat. So totally no difference. Granted, flat is never totally flat, but I still don’t get it.

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