All About Erg Mode in Zwift

All About Erg Mode in Zwift

Erg mode confuses a lot of new Zwifters. What exactly is it, anyway? And when should you use it? Here’s a quick explanation…

What Is Erg Mode?

Smart trainers can run in different modes which determine how much resistance they apply while you ride. The two most common modes are Erg and Sim.

Sim mode is simulator mode. This is the mode used in all Zwift activities other than workouts. In Sim mode, the controlling software (Zwift) sends parameters like rider weight, air density, Crr, gradient, and wattage to your trainer. The smart trainer then tries to replicate the “feel” of that virtual ride environment through its resistance on your drivetrain.

Erg mode is completely different. In Erg mode, your trainer’s job is to make you hold a particular wattage. “Erg” comes from Greek “Ergasía” which means “work”. Erg mode is literally forcing you to work at a particular level.

Example:

  • Your Zwift workout interval wants you to hold 200 watts for 10 minutes
  • If you are spinning at a cadence of 90 and putting out 200 watts, then slow your cadence to 60, your trainer will quickly increase resistance so you are still holding 200 watts even though you are pedaling slower.
  • If you are spinning at a cadence of 90 and putting out 200 watts, then increase your cadence to 110, your trainer will quickly decrease so you are still holding 200 watts even though you are pedaling faster.

Erg mode simplifies your workout, so your only job is to manage your cadence. You don’t need to worry about shifting (although it is certainly allowed), or whether you are hitting your wattage target. You just need to keep your cadence where you want it, and the trainer will make sure you’re hitting the target power.

When Should I Use Erg Mode?

Use it for workouts where you want to hold particular power levels for particular intervals (which is most workouts). Erg mode is enabled by default if you begin a workout while using a smart trainer in Zwift.

I’ve been asked if Erg mode should be used in races. First of all: this would be a little challenging to implement given Zwift’s event functionality. But even if you could do it, why would you? Racing requires constantly adjusting your effort to stay with the pack, attack on punchy climbs, ease off on descents, etc. Erg mode was not made for on-the-fly adjustments.

That said: you could use Erg mode in a race by pairing your smart trainer to your bike computer, and controlling it in Erg mode there. (You wouldn’t pair anything in the “controllable trainer” box in Zwift.) This may be interesting in a flat TT race, where you want to hold very particular wattage for certain amounts of time.

How to Disable and Enable Erg Mode in Zwift

You can disable and enable Erg mode from the workout browser screen by toggling the “Use Erg Mode” button.

You can also turn it on or off during your workout by clicking the up arrow, or clicking your mouse near the bottom-middle of your screen. This will bring up a menu which includes a button for turning Erg on and off (see below). (On iOS or AppleTV swiping up will let you access this menu.)

Lastly, the Companion app has a button to toggle Erg on and off during your workout.

What Gear Should I Use?

While Erg mode will work in any gear on your bike with no shifting required, riders often ask what gearing is best. There is no clear “right answer” for everyone, but here are a few things to consider:

  • If you want to work on climbing, train in a climbing gear (small ring on the front). This will reduce your trainer’s inertia, mimicking the feel of a low-speed climbing effort where your muscles aren’t able to “coast” as long at the top and bottom of each pedal stroke.
  • Train what you race. If you’re training for a particular type of outdoor race, use a gearing that mimics the pedal inertia you’ll be experiencing during the race. So a flat TT might use the big ring and one of your smaller cogs in back (high inertia), while a hill climb race might use the small ring and a big cog in back (low inertia).
  • If you ride a lot of Erg workouts, you might consider varying your gearing in order to wear your cassette more evenly. If 90% of your riding is in the same gear, you’ll wear out your cassette prematurely.
  • Chain line is always a consideration. Although your trainer and bike may allow it, having a bad chain line will increase drivetrain wear and wattage loss. So if you’re in your big ring in front, try to stay out of your easiest gears in back. And if you’re in your little ring in front, stay out of your hardest gears in back. Try to keep that chain line as straight as possible.
  • The lower your trainer’s inertia, the faster it can change resistance between intervals. If your trainer is slow to respond, and/or you’re doing very short intervals, you might consider shifting to the small ring to help your trainer respond more quickly to resistance changes.
  • Noise may also be an issue with certain trainer setups. An easier gear (small ring in front) should reduce your overall spinning and thus the overall noise level.
  • Shifting is OK: there are times when shifting at the start of certain intervals may make sense. Read this post for more thoughts on this topic >

For more info on the muscle recruitment side of things, check out this video from our favorite Aussie Lama:

The Spiral of Death

If you understand how Erg mode works, you’ll understand what we like to call the “Spiral of Death”. This torturous event happens when you are in Erg mode attempting to hold a particular wattage, then your legs get tired and your cadence slows. In order to keep hitting the wattage target, your trainer will then increase the resistance (see examples above).

This increased resistance naturally slows your cadence even more, which means the trainer piles on more resistance… until you come to a grinding halt.

Feeling the spiral of death beginning? Ramp up your power a bit while shifting to an easier gear so you can raise your cadence. If you’re out of gears, the only way out of the spiral is to push harder, increasing your cadence so the trainer will reduce its resistance.

Questions or Comments?

Still confused about Erg mode? Got some insights to share? Comment below!

About The Author

Eric Schlange

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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Alan Jolly
Alan Jolly
1 year ago

Great article. I have a Garmin Edge 520 that I rarely use and never indoors. I had no idea that I could use it to controll my trainer. Just watched a Garmin tutorial video and looking forward to playing with it. I still guess it’s easier to use the Zwift workouts but still something new to play around with.

John Grenfell
John Grenfell
1 year ago

Would be really interested to read about SIM mode and more specifically the causes of lag ie time it takes for traineer get the message of adjustment and lag of mechanical action across various traineers. Is Ant+ quicker than BLE? Which trainers have less lag? I’ve looked at a lot of forum posts in an attempt to help troubleshoot issues follow riders have but with your expertise on the issue it would be a great resource.

Paul Hayward
1 year ago

I always use to use erg mode but I now prefer to use slope mode so that I control my own power rather then the trainer.

Art Weeks
Art Weeks
1 year ago

Does climbing the entire Alp in Training/Erg mode count as a trip up the Alp? Do you get the spinner and a shot a the wheels?

MATHEW M ROSE
MATHEW M ROSE (@matrose617)
1 year ago
Reply to  Art Weeks

Erg mode is brilliant if you want the “blast off” badge. I set my trainer to hold 280 watts and did the 12.44 km of the Alpe in 50 minutes. It takes care of the route pacing for you and lets you focus on cadence and gear selection.

Arna
Arna
11 months ago
Reply to  MATHEW M ROSE

How do you set your trainer to hold 280 watts? Did you create a 50 min workout at 280w with erg? Or do you have a trainer with the ability to set watts? I don’t think mine does that. Cheers

.KR
.KR
1 year ago

Also, trainer difficulty off is equivalent to erg mode, yes? (No ability to test this with my setup.)

.KR
.KR
1 year ago

Though I suppose, no ability to set a target wattage..

Jim Mattson
Jim Mattson
1 year ago

One important point is that if your power source is the same device as your controllable trainer, then erg mode is implemented in the trainer firmware, with a tight feedback loop. However, if your power source is a different device than your controllable trainer, then erg mode is implemented in Zwift software, with a pretty loose feedback loop. In the latter case, you are more likely to see overshoot, which can be a problem when the power target changes significantly from one interval to another. (For example, the sprint intervals in Jon’s Short Mix are tough to hit with the… Read more »

Bob
Bob
7 months ago
Reply to  Eric Schlange

Can you help me understand this? I just did Jon’s Short Mix and experienced the difficulty with ERG on the sprint intervals. I’m using a Kickr Bike. What does it mean when you say the “power source is the same device as your controllable trainer”?

Bob
Bob
7 months ago
Reply to  Eric Schlange

Eric – what does it mean when you say “using your smart trainer as a power source”? What power are we talking about here? I have a Kickr Bike and am running Zwift on an Apple TV, fwiw.

Steve
Steve
1 year ago
Reply to  Jim Mattson

I have this issue with my Tacx Vortex smart trainer, which is a low end of the market one, while using my 4iiii left crank meter… ERG mode cannot cope with large, short, sharp increases in wattage. Brief high power sprints just don’t work, as the trainer is too slow to read the power, and adjust the resistance. For this reason I’ve had to abandon ERG mode for a lot of my training sessions, which is a shame, but it is making me more aware of what power I can hit in specific gears, and it’s teaching me to control… Read more »

Eibert Van't Hof
Eibert Van't Hof (@e_vanthof)
1 year ago

There is another way to get out of the spiral of death. Disable ERG shortly and get back to a comfortable cadence and then turn ERG back on. Worst that can happpen is losing a half star in a short interval 🙂

I needed it in the Hayman workout, which for me had way too brutal differences in those short sprints (which where way too high anyway for a climber like me) could not even get the cadence back up again in the rest in between.

sven
sven
1 year ago

To help avoid spiral of death, I always aim to be at a high cadence before I enter any high wattage block.

If you do enter the spiral of death in a Zwift workout, just give up – save those knees for another day. Zwift will disable ERG mode when you stop and let you get back up to power before enabling it again.

Mike Cox
Mike Cox
1 year ago

Thanks for that, most useful.

Derek
Derek (@dpr4473)
1 year ago

Good info. Especially on the “Spiral of Death.” I always felt things got weird when my legs would tire toward the ends of intervals, something more than just fatigue. I never realized the trainer was actually increasing the resistance to meet the power demands. Talk about a recipe for disaster.

Steve Reynolds
Steve Reynolds
1 year ago

Another recommendation on the “Spiral of Death.” Sometimes when you come to the end of a high power workout segment and are entering a lower power rest period, there will be a couple seconds of delay transitioning to the lower power. If you ease off of your effort too soon, expecting an immediate decrease in power, you may get a very unpleasant surprise as your legs grind to a stop/near stop. This could take enough out of your legs that it could affect the remainder of your workout. So power through those high to low transitions until your trainer actually… Read more »

steven howes
steven howes
1 year ago

Hey are we going to see erg control in free ride mode with the zwift app. This would be a great help thanks.

Joe Holmes
Joe Holmes
1 year ago

Has ERG mode been moved or changed?

Just done a zwift workout and there was no option to use erg mode, not on the phone app or whilst selecting the workout.

Using the same trainer I have always done (Elite Drivo I – the AT-T lookalike), no settings have been changed on my trainer, the only thing I’ve done is update Zwift.

Deanna
Deanna
1 year ago
Reply to  Joe Holmes

I had the same problem but realized after reading this article (link below) that for some reason I’d started pairing my trainer as a power source, not as controllable… haven’t checked this out yet as a fix but I’m optimistic

https://www.smartbiketrainers.com/zwift-connectivity-issues-troubleshoot-connection-issues-smart-bike-trainer-4533

Deanna
Deanna
1 year ago
Reply to  Deanna

Update: this solved my problem 🙂

phil
phil
1 year ago

I want to set a specific erg level and just ride til i decide to quit – not [art of a structured training workout. Is that possible/

Steve Reynolds
Steve Reynolds
1 year ago
Reply to  phil

You can’t just set an ERG level in Zwift and do a “free ride.” ERG mode in Zwift is only available as part of a custom or Zwift workout. But you can easily create a very simple custom workout in Zwift. Just make it one interval of a very long duration (longer than you’d typically ride) at whatever power level you want. You’ll then be able to ride at that power level in EEG mode up to the duration of the interval. You’ll also be able to vary your power +/- 10% and still stay in ERG mode or, at… Read more »

Adrian Amos
Adrian Amos (@ahamos)
1 year ago

Another consideration for wheel-on trainers is to pick a higher (more difficult) gear to avoid over-geared tire slippage.

Ward Strona
Ward Strona
1 year ago

I used to have a erg mode on my dashboard but it has disappeared for three weeks can’t find it can you help

MHolden
MHolden (@holdenadventures)
1 year ago

One of Llama’s earlier videos about Erg Mode sounded cool but the spiral of death was a bit intimidating. After a few workout sessions where my power was all over the place, I gave it a shot and WOW! Erg mode for the WIN! Spiral of Death is real but not too bad. Erg has definitely been a plus in making training more effective!!

Cody
Cody
1 year ago

I like using ERG, but I find sometimes later on in the workout it will be extremely late to change to the next block. This is was especially a problem when I was doing the Wringer and the wattage wouldn’t lower after the last hard interval.

Adrian
Adrian
1 year ago

There is no way to use erg mode and still get the simulation too is there? Or I wanna ride the Alpe at, say, 280, but still feel the terrain change…

Paul
Paul
1 year ago

No option to turn on ERG mode in workout- not visible as as option under the workout

Josh
Josh
1 year ago

Can you use ERG mode while doing a free ride (non workout) in zwift? Want to set it to hold 300w while going up alpe du zwift

Nathan
Nathan
1 year ago

Thank you this, I’m new to smart trainers and just hit the spiral of death!!! I thought the trainer had broken!!

thomas bunn
thomas bunn
1 year ago

Its been mentioned a few times 5 seconds before you hit the big watts spin faster ,but if you do get caught in the spiral of death don’t try and grind it out (you will damage your knees)just stop and wait a few seconds then start again ,you will get wise to it tho and spin faster at the end of your easy segment before you go through the arch

Owen
Owen
1 year ago

So this confirms that it doesn’t matter what my gearing is? ie in Erg mode I should still be able to hit the higher wattage short efforts, and it doesn’t even matter if I’m sat in 34×28?

I’m just about to upgrade to a smart trainer from a dumb one with speed sensor and struggle to hit the short high watt efforts at the moment, without my cadence being through the roof. There’s just not enough resistance. I thought I might have to change my drivetrain, but it seems maybe not with Erg mode.

A different Owen
A different Owen
1 year ago

Is the “spiral of death” less likely if you turn off ERG Mode Power Smoothing?

Harriet Wingfield
Harriet Wingfield
1 year ago

Hi, I am trying to turn on erg mode but when I bring up the bar along the bottom of the screen there is no ‘erg on/off’ button.
I am using an Elite Direto and running zwift from my ipad. Am I missing something?? Please help as my watts are allover the place on training rides!

Gregor
Gregor
11 months ago

Hello. I was riding workout in erg mode. Workout have also season of free ride. Suddenly no egr (rrrrr) mode anymore and no option to turn it on on zwift. Super hard sequence become super easy.
What I am missing on Zwift or at Kickr Core?
Best regards,
Gregor

Gregor Fras
Gregor Fras
11 months ago

Hello, I have question regarding Zwift workout. Some Workout are so structured that some start and end are like rump up (with erg mode on) but main part is free ride: high watt low rpm. But in free ride erg mode is turning off, so planed super hard section become super easy 🙁 And also button for rpm in Zwift companion disappears. What I am missing?

Wahoo Kickr Core

Best regards,
Gregor

Gregor
Gregor
11 months ago
Reply to  Eric Schlange

Thanks for fast reply 😊
So is normal that in free ride trainer goes to sim mode. In case there are flats or even downhill everything become easier then suppose 🤔
I have on lowesr gear.
Br,
Gregor

Smart Drive Beginner
Smart Drive Beginner
11 months ago

Omg… thank you

Vid Ingelevics
Vid Ingelevics
10 months ago

Recently, my Elite Drivo seems to be in constant ERG mode – i.e., the level of resistance remains consistent no matter whether I’m climbing, on the flat or descending but the speed indicated changes.There is nothing on the screen that allows me to turn it on or off and when I click the bottom of the screen none of the controls allows turning ERG on or off nor are there any arrows. Everything else seems to work. I’m using my older iMac as my computer connecting to the Drivo and my iPhone via bluetooth. It’s still a workout but I… Read more »

Vid Ingelevics
Vid Ingelevics
10 months ago
Reply to  Eric Schlange

It shows as being paired. But is that a function that is only visible through BT connection?

Vid Ingelevics
Vid Ingelevics
10 months ago
Reply to  Eric Schlange

Oddly, it just starting working again on its own after a month. I think it had something to do with failing to connect via BT but still don’t really know why.

Brian Kling
Brian Kling (@briankling)
10 months ago

OK I’m a newbie to Zwift and my trainer (Elite Suito). I tried to start my first workout but find this ERG mode impossible! I read and I get it that I should maintain my cadence and then it should work OK, regardless of gear. But yet when your route has an incline that goes up to 4%, 6% then suddenly I can barely crank it out, then I get stuck always in the “Spiral of Death” mentioned in your article. I don’t know how to proceed, I can’t seem to move forward out of this, always end up with… Read more »

Kyle Aubrey
Kyle Aubrey
9 months ago

Hi Eric. I really appreciate your insight on these issues and would appreciate your input. I have been using a Tacx Flux 2 in erg mode for awhile now. Obviously the resistance set by the trainer is based on your cadence at any given time. I find the built in cadence sensor in the Flux 2 to fluctuate very sporadically (up to 20 RPM jumps seems regular at times) and quickly (like using 1s power vs 5 sec rolling average). This makes it difficult for the trainer to maintain the programmed power for workouts and the power tends to jump… Read more »

phil
phil
9 months ago

Dear Eric, thank you for that nice blog entry.
I started Zwit Traininsplan FTP Builder.
ERG Mode is not working and there is no button to start it (as seen in your first screenshot (use ERG Mode)
I use Zwift with Zwift Compagnion app with Wahoo Kickr Snap via Bluetooth.

Thank you

phil
phil
9 months ago
Reply to  phil

Note: it was working great so far with my kickr. Has that something to do with the zwift traingsplan? Also checked wahoo app on my iphone, ERG Mode is enabled ther as well as ERG smoothing.

Phil
Phil
9 months ago
Reply to  Eric Schlange

will check that tomorrow !
thanks

app was off I am surey

question to the Setting of erg mode:

the only button for that I Know in Zwift -> workouts „use erg mode“

so if habe started a Zwift plan, I need to go back from the plan to workout tab and enable erg mode, then back to tab Trainingsplan and then to my designated next workout or ?

Dave Campbell
Dave Campbell
9 months ago

Thanks Eric, in TrainingPeaks, I can set a target range vs a discrete target for power. Do you know how Zwift in ERG handles the range?

Andy
Andy
8 months ago

I’ve just done a ramp test in Erg mode on Zwift and my power seemed to bounce around at a steady 85 rpm cadence (Elite Directo X). Constant messages of “not enough power”, “too much power” or whatever it was, and a power trace that bounces around as much as sim mode. Is this Bluetooth lag? Something trainer specific? Or my pedalling style?

Chris Potter
Chris Potter
8 months ago

If I want to do a custom workout from training peaks, but not have erg mode on, will Zwift go into Sim mode so I can work on pacing with gradients etc, or will it defer to slope mode and not have any of the gradient changes etc?

Jane Ridley
Jane Ridley
8 months ago

Wattage and Cadence readouts on Zwift spiking. I want to SPEAK to someone who understands how all these systems work so it can be put right. I am not an engineer and can’t understand solutions put on forums.

Hayley
Hayley
7 months ago

I dont have an option for ERG mode. Do you know why this is? i have a wahoo kickr core.

Jeffrey Forrest
Jeffrey Forrest
7 months ago

My ERG button has completely disappeared when doing training rides. I use a wahoo kickr core and run zwift thru apple tv. The spot on the companion app where the erg button used to be is now blank. When I run a training ride thru my iphone erg is there, but not when I run it thru apple tv. Thanks for any help you can give me.

Jeffrey Forrest
Jeffrey Forrest
7 months ago
Reply to  Eric Schlange

That did the trick. Thanks very much.

James Metcalfe
James Metcalfe
6 months ago

An issue has occurred where resistance on trainer goes to zero, so zero watts is delivered despite pedalling when attempting a workout in ERG mode, and the avatar stops in the road. How do I stop this happening again?

James Metcalfe
James Metcalfe
6 months ago
Reply to  Eric Schlange

Eric thanks for responding. Wouldn’t issues with ANT+ drop out affect all riding on zwift and not just workouts? I’ve never had an issue where resistance does not not reflect gradient on a non workout ride.

Stephen Done
Stephen Done
6 months ago

Hi Eric,
Another advantage of erg mode is that you can use a cheap single speed bike on your turbo for workouts. I.e. you don’t need any gears on your bike. Of course, Zwift gets a little trickier to ride in SIM mode on a fixie!

SimonM
SimonM
27 days ago

Had trouble with accessing erg and steering mode on a Wahoo Kickr bike…eventually realised that when on the pairing screen, you have to activate the “controllable” icon 🙂

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