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!
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.
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.
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.
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?
Yep!
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.
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
Also, trainer difficulty off is equivalent to erg mode, yes? (No ability to test this with my setup.)
Not at all. ERG mode will change resistance to have to hit a particular wattage. Trainer difficulty off = no resistance changes. Trainer difficulty off is the same as having a dumb trainer, basically.
Re trainer difficulty, i just saw an YT video explaining that the Trainer difficulty basically is changing the gearing, the wattage needed form start to finish is exactly the same wherever the slider is, only difference is the feeling of a lower gearing the more you push the slider to the left , and higher gearing the more you push it to the right. Is that statement wrong?
That statement is basically accurate, but ONLY ON UPHILLS. On descents, the trainer difficulty slider has the opposite affect in terms of “changing your gearing”.
That’s why I prefer not to use that analogy. I think it’s confusing. Much simpler to just say it’s changing how much gradient feel is being sent to your trainer!
Though I suppose, no ability to set a target wattage..
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 »
Good point, Jim! You definitely get tighter intervals when using your smart trainer as a power source.
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”?
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.
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 »
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.
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.
Thanks for that, most useful.
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.
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 »
Hey are we going to see erg control in free ride mode with the zwift app. This would be a great help thanks.
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.
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
Update: this solved my problem 🙂
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/
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 »
Another consideration for wheel-on trainers is to pick a higher (more difficult) gear to avoid over-geared tire slippage.
I used to have a erg mode on my dashboard but it has disappeared for three weeks can’t find it can you help
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!!
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.
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…
No option to turn on ERG mode in workout- not visible as as option under the workout
Then my guess would be you haven’t paired a smart trainer as a controllable trainer.
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
Thank you this, I’m new to smart trainers and just hit the spiral of death!!! I thought the trainer had broken!!
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
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.
Yes, in ERG mode the gearing setup of your bike basically doesn’t matter. Because you don’t need to shift in ERG.
Is the “spiral of death” less likely if you turn off ERG Mode Power Smoothing?
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!
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
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
If the free ride section is too easy, just shift to a harder gear. I assume you’re riding ERG in a very easy gear… that’s why it’s so easy once ERG is turned off.
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
A free ride section shouldn’t be SIM mode – you shouldn’t feel inclines and downhills. It’s just a flat resistance (like riding on a flat rode) regardless of road incline.
This is done so you can set your own effort level.
Omg… thank you
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 »
Sounds to me like you don’t have your trainer paired as a “controllable trainer” in Zwift.
It shows as being paired. But is that a function that is only visible through BT connection?
No, the trainer’s functions are the same for ANT or Bluetooth.
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.
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 »
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 »
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
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.
Make sure you’ve paired your KICKR as the controllable trainer in Zwift. And turn off the Wahoo app while running Zwift, just to make sure it isn’t controlling your trainer instead of Zwift.
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 ?
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?
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?
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?
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.
I dont have an option for ERG mode. Do you know why this is? i have a wahoo kickr core.
It means you haven’t connected your trainer as a “Controllable Trainer” in the pairing screen. That, or you aren’t in a workout, which means you won’t have the ERG option.
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.
Sounds like you need to pair your KICKR as a controllable trainer on the pairing screen.
That did the trick. Thanks very much.
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?
If you’re connecting via ANT+, here are some tips: https://zwiftinsider.com/how-to-fix-ant-dropouts-in-zwift/
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.
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!
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 🙂
how do I tell, in the app, to what power ERG mode is set? I assume the up/down arrows (though there are two sets?) control power?
i have to do a workout.
8min at 90percent of hrMAX
can i ride on free zwift maps and give the resistance with erg to reach my 90%
because like this …(workout for a study) setting a wattage woul not work…
i need to put on or off resistance during workout
There must be a bug in Kickr Core or in Zwift. I have only 1x in front (48). When I use ERG mode and a climbing ring in the cassette, the the watt from kickr core and the power pedals (which run autark) differ about 15 Watt. When I use a small ring in the back (flat area) the watt come very close together. So the big trick to go fast on Alpe de Zwift is to use ERG modus and the biggest gear you have… I will try this at Alpe de Zwift and compare (biggest and smallest gear)… Read more »
Make sure your firmware is up to date, and you’re all calibrated.
Today I made some ERG mode testing at exact 200 watts of the kickr core.
All firmwares up to date and all calibrated. Spindown in wahoo app and the Assomia pedals set to 0.
Smallest gear:
rpm watt hr
100 212 134
50 210 126
Biggest gear
100 217 135
50 205 124
Medium gear
100 206 132
50 210 123
So conclusion for best time on alpe de zwift => Biggest gear with lowest possible cadence!
Will test this!
May I know is it normal when doing workout thru Zwift, it always showed “ERG mode disabled temporary”. After that another msg prompted out “hold steady to re-activate ERG”. The last msg “Re-activating ERG” prompt out. These 3 msg repeatly prompt out during the workout. This caused me frustrated and stop the workout.
I did calibration twice and updated the firmware before the workout.
Thank you
Jane Ng
I did a workout today up the Alpe and didn’t want ERG mode because i wanted to try to hit the workout’s target wattage myself while also feeling the route’s actual slope so I disabled it. It didn’t switch to sim mode. Instead of forcing the wattage prescribed by the workout based on cadence and torque, it ended up as if the workout was in “free ride” mode which is the same as riding on a flat the entire time. AmIRite?
Hi Eric,
hate technology, real struggling to find support also…
Since 2 updates ago I no longer have ERG mode, the icon has gone as well, has something changed for just me or everyone? Bit of a pain doing workouts as power now seem to fluctuate +/- 30 watts and have to use the gears.
Make sure you have your trainer paired as “controllable” in the pairing screen (bottom right).