For those who still are not understanding why trainer difficulty is not "like gearing" here is a scenario with some additional specificity that may clarify things: Let's say for instance you it a 15% grade, challenging for most mere mortals, at 100% difficulty you will face that with all the resistance commensurate with that gradient. It will be very difficult and you will have to use likely a very easy gear to apply power to the pedals. Let's say a 50-32 gear ratio for the sake of argument. There is a minimum amount of power that is going to be required to overcome that resistance and if you are incapable of producing that power, you will not be able to move the pedals. Now, let's say you reduced the difficulty to 50%, now you've halved the resistance and can very likely move the pedals because your power is sufficient to do so. Zwift will allow your avatar to move up the road based on that calculation, however, in reality, you likely would be stopped on the side of the road in the real world because your power/torque capacity does not meet the inertial requirements to move the bicycle. The slider is making the hill easier while applying your actual output of power to calculate virtual speed. Moreover, the trainer difficulty slider affects the descents as well allowing one to continue to apply power in areas that they very likely would spin out. This again is calculated and will produce a speed benefit that would not be possible in the real world or at 100% trainer difficulty. The slider isn't gearing, it's realism effect.

Wow, what an excellent video! As a new Zwift rider, I’m surprised at how untransparent the details of Zwift are. You are the best teacher, cheers.

Excellent. As clear minded a description of both the science, bike function, gaming situations and application as you’ll ever find. Well done.

Wow what an excellent thorough video and how all this really works. I couldn't wrap my head around it but you have explained it perfectly thanks so much!!

Really enjoyed your video talking about this. I've always wanted my difficulty set to 100% but you make some good points about gearing and injury....I went through a month of knee strain and can totally see a use there. Thanks again!

Perfect. Now I know how I want to adjust this setting depending on the ride/day. Thx 👍🏻

Thanks. Good explanation thqat this is really another tool to manage the Zwift experience. I'll definitely be testing and playing with it.

My trainer bike is a 9-speed. And because of that the gaps with the standard cassette had big gaps. I replaced it with a 14-25T. I would NEVER put my old knees through that gearing outdoors. So, I have to set Zwift difficulty to save my knees. No crazy low cadence stress on my knees. Good that the video confirms my instincts.

This channel is purely stellar. Keep it up and thanks for sharing your knowledge!

Hi Sarah! Your viedos about Zwift are just about everything you need to know about Zwift. I completely understand how things work in Zwift when watching your videos. Keep up the good work! /Pär from Sweden

Not everyone is a 25-year-old racer. I'm a 67 year-old, 190 lbs, Zwift user who has been cycling for 60 years. There are long climbs on Zwift that I want to ride but my knees can't take the long-term stress. So I adjust the difficulty. When riding on flatter routes, I go back to 100%. For me, adjusting the difficulty has made Zwift a better training tool

Excellent explanation; it reinforces what I kinda already understood. In other words, your video gives me confidence that I understand the purpose and application of Trainer Difficulty. You covered my use case... injury. I have a worn out hip that will eventually need to be replaced. Of course I am in no rush to go thru this procedure. The injury is from years of running; I can’t run anymore but I can cycle. I live in flatland and riding outside is... flat. On Zwift I want to experience the various routes/terrains and I could not do many of the climbing routes without the Trainer Difficulty reduced. If I did use 100% I’d have to ride once and recover for a week or maybe even longer. Trainer Difficulty reduced keeps me on the bike and out of the hospital (for now). Thank you for your time; your videos are always spot on.

Very informative - thank you for the detailed explanation!

Hey thanks Sara for making this video. This is the best explanation I've found so far. Cheers..

New to your channel and just subscribed; this video is insanely brilliant, loved it, thank you 🙏

Thanks for taking the time to break this down for us this clearly. 100% trainer difficulty for me, though. GFNY coming up in a few months and I need as much help in my uphill training... no real hills in Chicago 😉

One of the best explanations on UKposts regarding cycling / Zwift / training science. Enjoying it greatly!

Thank you for this video. I'm fairly new to turbo trainers and Zwift and i have only just discovered your channel on UKposts. I loved the content. It back up my understanding - I have my TD set at 90% as my indoor trg bike has a 34/29 easy gear whereas my IRL bike has a 34/32 gear so hopefully the adjustment will better reflect my IRL experience (though without the weather or the cafes).

Thanks for sharing, explained really well. Love your updates 😉

Great explanation. But I found out that if you get your cadence in the same region as you would normally do, you still have to change gears in 50% as much as in 100 %, but you use bigger gears. The wattage I can produce are the same in both settings with the same cadence but the trainer is just spinnig faster since the gear ratio is different. The problem you describe gets real in the zone where you are grinding in the smallest gear and can’t spin up to those higher revs. This is were it gets easier on your legs when you move the difficulty lower since you are than able to use higher cadence.

Great video and great explanation. As someone new to Zwift and new to cycling this will be extremely helpful as I would like to race in the platform at some point.

Just 3+ months into Zwift myself and found this video absolutely brilliant. Thank you so much!!

Another excellent video. Your knowledge is extensive. Thanks for sharing some of it.

You have a gift. It can be a rare thing indeed that a very smart person can explain a complex topic in relatively simple terms that those with lesser levels of understanding can grasp and apply. This video is a great example of such a rarity. In college, my metaphysics professor Van Hook said something that stayed with me to age 65: “if you cannot explain it, you don’t really know it.” Well done professor!

Thank you for this video. After watching this I decided to bump up this setting tonight. I was able to keep up the same pace with a higher wattage output. I'm going to try to keep bumping up this setting.

Very informative. I'm recovering from an injury and can only spin with little resistance. Playing with the difficulty is just what i need to keep me on Swift. Thanks!

This is excellent so well explained and all is NOW clear.. I am new to Zwift and this is super helpful… have a great 2022…

Brilliant explanation, Sarah. Thank you.

Excellent clear and informative explanation. Thank you.

I'm a newer sub and wanna say thx for you knowledge and experience with riding and zwift. I just setup my Saris M2 trainer yesterday and am binge watching alot if your videos to really get a grasp of Zwift. I've done a ride to get the feel of it and want to know where to start ie: settings, FTP test, just getting to know how best to approach the platform. What would you do etc. Sometimes I get overloaded with to much info and kinda want a general direction from square one. Hope I'm not asking too much, thanks alot, in the meantime I'm just f'ing around with getting to know the landscape🙂

Thanks for this. New to zwift and was trying to wrap my head around this very thing in the software that I didn't know existed. I knew I had a question, but didn't know what it was. So now I know the question and the answer. 😉

never new about this setting - thanks - very well done -

Excellent explanation. Really good and well put.

That was fantastic! I finally understand after many years on Zwift and. many confusing explanations.

Love the way you explain things!

Only just starting Zwifting last week. I did the KOM with the radio tower climb on the Tour of Watopia a few days ago not knowing what I was getting into. Even at 50% difficulty I was toast. Felt like such a massive achievement just getting to the top. Now I know it should've been twice as hard! People are machines

Thanks! Very helpful. Been road cycling for about 50 yrs. On Zwift for about a month . Lucid.

Best Explanation I’ve heard...thanks!!!

Awesome content, thank you so much

I've been bicycling for about 5 years, but have only started gradually pushing myself for the past 3 years. In the summer, I ride about 250 to 300 miles a month. I bought an indoor trainer because I live in Michigan and it's just to cold and quite frankly, unsafe to road ride in the winter. Seems like every year I've gotta restart from square one to get back in shape. As a newbie who just purchased an indoor trainer (Wahoo Kickr), I'm still learning Zwift and didn't even know there was a difficulty setting until after using Zwift for about 3 weeks. My first rides on the flat route were crazy difficult by comparison to my normal rides. I ride on some pretty hilly roads and at 100%, it was definitely more difficult than riding outside. My setting was at 100% by default. I didn't even know it. I had no idea how the setting worked, so I turned it down to 50%. To me, 50% actually felt more true to my usual ride experience. 100% was just over the top. My goal is to gradually push it up each month. Last week I moved it up a notch to what I'd guess is 60%? There's no associated number given so I don't know for sure. But my goal is to just keep progressing back to a higher difficulty each month.

New sub and I love your channel!!!❤

Excellent explanation for this newbie!

Great video! Have enjoyed learning from your commentary on various videos. I just got started on Zwift...so I have a super basic setup with a regular trainer with a speed sensor attached...does that speed sensor still enable Zwift to come up with a fairly accurate power calculation? Or is it a more estimated value based on my cadence/speed? And in that realm, will trainer difficulty have much affect? Thanks so much!

This was a really good explanation ... awesome vid. I know when I come to this channel to get some info I really don't need to look any further. The explanations is done in a easy to understand and comprehensive way

Great video! Well explained. I'm just not sure why there is so much debate. Anyone who has ridden a bike up a long, steep hill knows that you lose your legs faster grinding at 50 rpm than spinning at 85 rpm. The one issue I have with the settings is I feel MAX difficulty makes it feel harder than real world. I have no problem getting up 10 - 15% grades in the real world with the gearing I have on my bike. I can barely push the pedals over on the same type of grade in my lowest gear on Zwift. I'm not going to buy a different cassette when it works just fine for real-world riding; which is 80% of my cycling.

Wow, I actually understood that. Thx. I always use 100%, and train for epic real-world climbs, but great to know I can dial knee & quad thrash down for recovery(‘ish) rides.

If you're lowering the training difficulty (reducing the resistence) and flattening the climbs you are essentially just going for a ride on the flat, it's pretty simple .. the watts are measured by the pressure on the pedals from your effort but if there's no resistance you're not simulating riding a climb you're riding a timetrial, you might aswell ride fuego flats ignore the speed and just ride on rpm and power, it'll be the same effort and tension on your muscle groups... Great vid BTW 👌

Great video. Really explains it very well.

Very informative. Very new to Zwift but been cycling for over 60 years. I know realise why hill climbing seemed a lot easier than in real life and how to make it more realistic. With age I have found my hill climbing much more difficult if only I could adjust the gradient in real life!!

Excellent explanation about this subject

Clear and concise. Thank you.

Thanks for the information. Just started on zwift with my old classic dumb trainer. So on Zpower one month in. Looking at the smart trainers and wondering how it works with thoes devices. This video helped answer many questions. Will want to simulate the real world the best I can so when out it is the same effort. Live in a area with many hills and big mountains of various grades with very long false flats, so no true flats or easy rides where I live. Have to climb a 10%+ hill I live on to home every ride.

Great video! I've been Zwifting for 2 weeks now and I only have a 2x9 speed bike. My bike has a 25-13 cassette in the back which is HARD when it comes to climbing. I have it set at 50% until I can upgrade to a 2x11. Thanks!

Good explanation. I was really impressed with difficulty at 100%, it really felt like an actual 12% gradient. Anyone who has ridden steep gradients in the real world will understand the difference. I use 100% for training and 30% for racing lol.

Im glad somebody actually picked up, that sometimes zwift is just to ride and have fun. Sometiems you might want to get on small races, even if your knees can go very fast, but cant stand a lot of pressure. This makes it actually fun, and allows you to maintain therapy or just "body maintenance" .

Very good explanations in this video. Going the same speed no matter the Trainer Difficulty holds true IF you put out the same watts (this has been proven). But in reality this may not be how it goes for you. On a steep/long hill you may not have the gearing or leg strength to maintain the cadence to achieve those watts (this was touched on in the video). So your watts will drop and you will go slower. But if you lower the difficulty and can maintain the same watts you would go faster.

Thank you, a very good info!

Excellent info thank you.

👍 I set my preferred 'Trainer difficulty' according to how I can do the Radio Tower climb. Then youll be able to climb everything within your gearing in Zwift.

Fantastic explanation best I have seen. For me i don't see the point having a virtual world with ups and downs and not experience them as it looks. You lose all the emersion of being in that virtual world. I want a tough hill to feel like a tough hill so it's 100% for me in trainer difficulty

This was great. Thanks very much!

Timestamps: 0:00 Vlog/Intro 3:34 How Zwift calculates speed and power 12:54 How Trainer Difficulty Works

Thank you. I'm new to zwift and this was a great explanation. Rational and poised.

I will prefer to keep the setting between 33 and. 50 percent because I don't race and I am not trying to destroy my knees. I know I would have to shift twice as much if I cranked it all the way up, and I've definitely noticed that the surge and drop power pattern at 100% adds time to most courses. I take about one to two minutes longer up the Alpe (and get a slightly lower average power) when I am shifting all the time at 100%.

Thanks as I’m a newbie very much appreciated cheersTony Tassie

Quick question. Can I use Zwift companion to navigate the screen instead of hard to use Apple TV remote?

So helpful. Thank you

Trainer difficulty allows you to stay in your comfortable cadence/torque window. This allows one to be more efficient on very steep climbs with typical road bike gearing. In real world you cannot trade of gradient for distance. Difficulty is like zig zagging up a hill.

Great video, you just earned a subscriber :)

Nice video...the algorithm should take a real time weather forecast into effect for wind obviously. As for rolling resistance, that too can be made pretty easily.

Hey. Great info about trainer difficulty. Thanks. Very clear and precize explenation. One remark: power is equal to TORQUE x ANGULAR_VELOCITY (P = F x R x ω), here ω is angular belocity of the crank. R is of course constant, you can not change it. F is the average force you press on one pedal times 2. Now, everything is said and all conclusions are totaly clear. The only extra information you need to have is that the level of difficulty set in game corresponds to the slope inclination expressed in % ( which is equel to sin(α ), where α is an angle of the inclination).

Great video well explained

Very well presented. I am impressed at your presentation and I suspect you must also be a very strong cyclist. I am about to move from a dumb trainer to a smart trainer for those indoor days and I'll admit, I am worried about that Watopia climb to the radio tower with its 17% grade and this trainer difficulty. I expect that I absolutely will not have the legs or gearing for that climb at 100% trainer difficulty.

You're a friggin guru. Subbed immediately after watching!

thanks for the explanation

Great explanation! Not only regarding how this setting works but also the basic rationale for its existence in the context of Zwift accessibility. I'm a new Zwifter (after many years on Computrainer software) and considered this difficulty setting to be akin to a gearing compensator. You've given me more to think about so thanks for that as well!

Thanks for the information and I wish would have seen it before I bought a compact crankset. 100% or Die.

Interesting! I'm fairly new to this, but I've noticed that weighing in at 90 kilos I seem to be able to pass riders by when going down hill when they are at a higher wattage, I presume this is due to gravity or am I putting too much in to this? Also does Zwift allow for age differences, I'm 62. I think you're right though, treat it just as a training tool and you'll be OK, my target this year is to lose 10 kilos for the summer. I try to train every other day, is it easier to do short rides every other day or long rides every 3/4 days?.....Keep your fingers crossed for me!!..Great video, you have another subscriber,......Keep safe.

what to do if in chainring 34 you can no longer do more speed because the Cadence is too high, and others on the 48 chainring are going faster than you. There is only one way out - change the bike? Or can this be compensated for difficulty?

Fantastic explanation, I’m new to zwift and your explanation was one of the most comprehensive I’ve seen! Thanks for taking the time to put together such an informative video

My bike doesn't shift fluently (not like I want to, also I need a new chain/cassette) so I turned it all down to minimize shifting as much as possible. Also I find it hard to see if or how much I'm going up or down so I am always too late shifting.

I like teh idea, "zwift is to have fun, to get you rolling". It also gives you teh option to be a "profesional trainer". It ahs a lot of "elasticity" to fit the users needs. Some of us want to (and are able) to go up to 1000 watts, some of us canot, but still want to "play". It is a program geared to the users needs. LOVE IT !!!!

I see Zwift as a workout platform never touched default and longer climbs kick my ass. Watts are watts, you need a certain amount of power to overcome resistance no matter the trainer difficulty. I’ll try 100% next time, curious.

Could setting it to 💯 possibly prematurely exhaust the output of the unit ? 🔥

Very well explained 👌 thanks Just enough physics for me!!

Does having difficulty at 100% wear your smart trainer components more rapidly?

Great video!!!!!!! What about Power Display 3 seconds and instant? I think the default is 3 seconds but I've notice you have yours on Instant. What the advantage? Thanks for the video and your time. Have a great day, stay safe! -Paul

Awesome explanation

If I understand you right, trainer difficulty only affect climbs ? In your option, shouldn't Swift put a limit of let's say 75% difficulty for race events ?

This is the best explanation of trainer difficulty I’ve seen 👏

Hi Sarah , the way i look at Trainer Difficulty is its a rear cassette choice just like in real life , i wouldn't try to go up ALPDZ on a 25 , i prefer to go big gears lowish cadence , some people spin , spinning would kill me !! Froome / Contador regularly used 34's . Great video , I hope i haven't misunderstood your video.

This is a great video even though things may have changed over the last 4 years. I’m 6 months in but I don’t feel that I’m progressing fast enough. I have a Zwift trainer with the cog wheel that replaces the cassette and gives you access to many more gears. Perhaps a video on how to increase you FTP would be good.

would you agree that if i want to climb alp to zwift in one hour , regardless of what the settings is , i still have to put out the same amount of watts to get up there ?

Great run through of the science behind how this works and why you might change it to suit your needs. I spent 2 years on a basic wheel on trainer using speed/cadence sensor for zwift to derive wattage/kg and speed etc. I could pretty much stay in one gear and spin up/down throughout any workout. Having just got a smart direct drive trainer, it is a completely different game to get that wattage out. I run out of gears at both ends, spinning out at speed and running out of teeth on the hills. The trainer difficulty is part of that mix that i can use to help but like you say, getting the right gears on my bike is what i need to do really, so i am prepped for real life rides.

Does the resulting resistance created by changing the trainer difficulty take weight into consideration? Im new to Zwift. I am very small/light and even at 50% trainer difficulty the gradients in the virtual ride require a much lower gear than those same gradients outside on the road. If weight isn’t factored in, seems it really can’t accurately reflect resistance of a grade for a given rider

Really good. Thanx

2 riders of same mass putting out same power one with trainer difficulty set to 50 one to 100 both finish at the same time. However one has climbed real world equivalent of 10 percent climb of 2km length. One has climbed a real world equivalent of 5 percent climb of 4km length. Is that right?

This is another excellent vid! However, my settings screen is very different from yours! In fact, my setting screen has no “trainer difficulty,” no “leaderboard,” or “pain level!” What is wrong? I have a Saris H3. Help!!!

Thanks for this video.really clear compared to dozens similar videos I watched even from ZWIFT Gurus like Shane Miller

You’re totally awesome 👏🏾👍🏾👊🏾