Seems like ERG isnt all its cracked up to be

So i’ve trained exclusively in ERG since i got into cycling 4 months ago. I thought being able to maintain these watts without thinking and without being able to back off would make me progress much quicker than in normal resistance mode…

It appears i was wrong.

Anyway, i went into zwift to try and ride in group for the first time. I tried to maintain the same watts consistently and found it a real struggle. What i could do for 20min sweet spot intervals in trainer road ERG was significantly harder to maintain in a normal resistance ride for just 10 mins, i just couldn’t do it. My power was spiking all over the place and it brought my average down a lot. The result was a significantly hard time and quite a low average power for the ride.

Anyway, i decided to record a training ride in TR with ERG mode, and use a power metre to record the same ride and see what i was actually putting out.

Here is the comparison.

As you can see, my power metre (up top) shows really large spikes, going down to 76 watts and then up to 250+ consistently . It appears i cannot maintain proper force on the pedals or keep power in a tight spread. This is why i believe i have a hard time actually maintaining constant power in normal rides. Has ERG given me a really false sense of training?

I know there is power smoothing, but i didnt think the difference would be this large.

So what do i do?

A) Lower FTP and do rides in resistance mode, learning to actually maintain required output

B) Just carry on with ERG and realise these numbers are really inflated

C) Look at my pedalling and learn how to apply power more evenly? Whats the best way to do this

Any thoughts here?

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Do the same test but do the second 20 minute interval in resistance mode, then compare the data.

And yes, I recommend mixing your workouts between ERG and resistance mode. I do almost all of my Z2/3 workouts in resistanc mode, and VO2Max workouts in ERG mode. I don’t believe ERG harms your ability to make power or that’ll be a stronger rider only using resistance mode. It is good to mix it up though, and focus pedaling technique. If you think you have an issue holding sub-threshold power in resistance mode then work on that more.

What were your power sources here? Were you using the trainer power for TR and your power meter for Zwift?


No i used the same trainer power for both my previous ERG workouts and the zwift ride.

I only got the power metre yesterday

It IS that large.

Don’t think about maintaining watts when you’re in Zwift. Just think about staying in the wheels.


Or to put it another way, the ability to put out smooth consistent watts has 2 applications. Doing training intervals and doing time trials or maybe long climbs.

In any other real-world riding situation, a smooth power profile is rarely desirable and rarely possible.

I’d agree Erg is not all it’s cracked up to be, part of the hype is from people who get artificially smoothed readings and therefore think they are super aligned to their workouts. Not their fault obviously.

I’ve also been using a smart trainer in Erg for the last several months and I’m persisting with it, but it does miss sprint intervals and require super focus on consistent cadence which doesn’t always suit the workout.


Is this a fundamental flaw in my technique maybe? Probably something i should have focused on rather than jumping on erg and thinking i dont really need to think just follow this and ill be a good cyclist :sweat_smile:

Such a steady power output (as the one you show in the graph) looks to me like a trainer smoothing power readings… my ERG looks nothing like that. (for reference, here’s a chunk of Lamark with ERG from last week):

(yes, by the fourth interval I was suffering like a dog :rofl:)

What trainer are you using? Have you turned off power smoothing?


Its the Kickr Snap

Power smoothing is turned on. I know it smoothes it out but i didn’t realise by just how much. It puts you in a false sense of security if you dont train any other way.


Grats on the power meter, I’m jelly :smiley:

There’s a couple things I notice with the screenshots you posted:

  1. In the TR screenshot, a wattage line that perfect means your trainer is doing its own smoothing and reporting smoothed power to TR. Raw power is pretty janky. (The ‘power smoothing’ setting in TR affects your live watts display when you’re in a workout, not the data reported in the graph.) By way of example, here’s a 15-minute interval in Erg mode from my old wheel-on smart trainer:

and here’s the same interval (more or less), still in Erg mode, with my current direct-drive smart trainer (cost about twice as much as the wheel-on):

The jankiness is less of an Erg-mode thing and more of a ‘how-does-your-power-source-report-power’ thing. Your power meter isn’t doing any smoothing, and that’s why you’re seeing such a jagged line.

  1. Your cadence line has a lot of variation. When you’re in Erg mode, your trainer will try to adjust its resistance to make up for changes in cadence and keep you at the same power target. When you’re in resistance mode, your cadence and gearing are the only things that control your power consistency. If you’re swinging between 80rpm and 100rpm (or thereabouts) in the same gear, you’re going to see that variation reflected in your power output.

Can you post screenshots of the Zwift ride that gave you trouble?


Is this the issue? Did you jump on zwift and ride with your PM for the first time and find it harder? Perhaps there is a difference between your trainer power and new PM. If the PM is reading lower, you are going to find the same workouts harder.


Hell yeah, even worse: some trainers put out the power you set if you keep the pedals turning :slight_smile: You said 250? It’s going to read 250 even if you are pushing 400 (or 10)…

No i got the power metre after the zwift ride

Even if i turned power smoothing off my spread would be nowhere near as tight as that.

I think youre right its a cadence issue.

Maybe I have got used to changing my cadence in erg mode. Essentially spiking the power, which decreases the resistance. I ease of and my legs recover, so they spin slower, which increases the resistance and i increase the power again, going in a big cycle of alternating extreme power rather than maintaining steady watts…

Probably need to work on maintaining a steady cadence all the time and applying power throughout the pedal stroke then.

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I MEAN, maybe, but also my trainer might still be doing smoothing, just a bit less than yours. I haven’t actually looked at the device configuration, so it’s set to whatever the defaults were. :sweat_smile:

Yes, exactly. Your averages will hit the target but you’re loading up your legs more than you need to.

Yeah, give it a shot! I don’t know if you’ve covered the sweet-spot workouts in the Sweet Spot Base plan, but virtually all of them have some sort of cadence drill built in.

If i started with my Wahoo Kickr an TrainerRoad i did the mistake to pair both Woahoo Kickr AND my inbuilt Power2Max with TrainerRoad. In this workout you can see the difference as i unpaired my Power2Max Powermeter (around Minute 28´)
@GiacomoRz @Mitch54321 #equipment #trainerroad-software

In following workout i paired TrainerRoad with my Kickr (ERG Mod) and my Forrunner watch with the Power2max just to watch the Data after the workout.

I have just started SS Base 1. And put in SSB2 and General Build 1 into my calendar.

Time to start training from the beginning and switch up modes this time.


Wait… what?? WHAT??

I have a Tacx Neo 2… should I DISABLE power smoothing on my trainer and let TR do the smoothing?

That explains a lot…

But honestly, I think TR should mention this more clearly. I ALWAYS use ERG mode on the assumption that that is the most accurate way to train with a direct-on trainer anyway.

I wasn’t aware that power smoothing by my trainer would distort THIS MUCH.

So chances are I have been “undertraining” in ERG because my trainer is smoothing?


I thought this could be it but i did record my power metre with my watch and used my laptop with trainer road connected to my trainer so i dont think this was the issue.

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