ERG or no ERG with Adaptive Training?

This is a potentially controversial topic, so let’s all stay curious and play nicely.

I’ve switched from Peloton at the beginning of the Pandemic to Kickr in 2021. On Peloton I was following the Power Zone Pack challenge and raised my FTP from 180 to 302W in just over a year (I checked the Peloton power with my power meter pedals, it’s within spec). On Kickr I started with the vanilla low volume TR program and then switched to mid-volume adaptive when it became available.

Well, I just did my ramp test and my FTP dropped to 205W—I lost 100W!

Now, there are plenty of things that might have contributed to this. Having a lingering cold for the last three weeks is not the least of them. But the decline has been gradual. So I’ve been trying to tease apart all the potential contributing factors.

The gear selection and the cadence might be among them. I used to spin closer to 100rpm in the heaviest gear—biggest ring in the front, smallest sprocket in the back. So I’ve been training for the flats, basically.

But lately, I’ve been also wondering if ERG could be contributing to this as well.

See, on the Peloton, I would try to ride at the top of the prescribed zone, and if I find it unsustainable for the duration of the interval, then I’d scale back to the middle or even the bottom of the zone. But on the Kickr with the ERG mode on I hold whatever power is prescribed regardless of whether I could put out more.

The hope is that the adaptive engine will notice that somehow and adapt my next workout. Again, I don’t know how the sausage is made, so this is all 100% speculation, let’s treat it appropriately. But I wonder if ERG is making it harder for AT?

Personally, this has nothing to do with ERG specifically. ERG gives you options to use for gearing (as you note) and if you want to perform at a level other than prescribed, using the Workout Intensity adjustment in the workout is as easy as fudging it with a Resistance/Standard setting and bike shifting.

I’d want to know very specific details on the testing you did before putting too much faith in the numbers. We have seen plenty of instances that even when keeping the same power meter, a swap from one trainer to another can lead to difference FTP results. Mainly, this comes down to effects and differences in the flywheel. Considering this is a change from a P bike with a massive flywheel, to the Kickr with a smaller one, that alone is a potential factor that must not be ignored.

Essentially, without lots more data about both tests, I don’t trust that data. Couple equipment changes with your recent illness, it just raises more questions than it answers.

  • How, exactly?

ERG is a tool for executing a workout. You can end up with the same basic demand via TSS, duration and power values in any mode. Considering that altering your actual demand via Workout Intensity can be done at any time, there is no basic difference or restriction when compared to the other modes. I just don’t see a correlation here when there are clearly other factors at play, that have already been seen to give measurably different results (gearing, flywheel speed, illness, etc.)

I don’t see apples/apples comparisons, not to mention all the fitness, training execution and illness issues.


I’m guessing your thought process here is that if a workout calls for 200 watts for 5 minutes and on the peloton it gave you a targe range of 190-210 you rode at 210. With the kickr now you are saying that it locks you in at 200 so you don’t think it is adapting you correctly since you can’t do the workout harder. If you put it in resistance mode and rode at 210 AT basically doesn’t care at this point.

Now if you manually bump or decrease the Intensity so it is actually telling you to ride at 210 and then you mark that workout easy I believe it should then factor that in and may increase how AT adapts. I have not confirmed AT changes being made to a bump in intensity but have lowered it (injured) and received a fail so I’m making the assumption it factors in bumps.

Short version it isn’t ERG creating the lack of progression in workouts or FTP you are looking for.


Don’t use ERG mode for VO2max work, use it for everything else.

Ignoring the 100W number, and accepting your statement that fitness dropped, I have a couple of immediate off-the-cuff reactions as to possible reasons:

  • volume decreased
  • if volume stayed the same, you may have been doing more intensity in Peloton than in TR
  • you need an off-season

Again I’m shooting from the hip, but those would be first guesses.

At the moment, think of AT as dialing in appropriate workouts in terms of difficulty. Based on completion and your feedback. The skeleton framework is the same for everyone in say SSB 1 LV, and the adaptations are there to give you appropriate workouts.


I could be wrong but I think there’s a suggestion that Peleton over estimates your true FTP and if you’re operating with a FTP slightly too high ERG will drag you into a Spiral of Death but setting a realistic FTP makes it a good training tool sometimes. There’s lots of threads on th pro’s and con’s if you search the forum.

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  • That is a common claim and observation, more so with one model than another but it is a good thing to consider. The OP did include this bit of related info:
  • So, depending on exactly how and when that comparison was done, it may reduce one potential variable.

  • Also, the unstated assumption here is that the power meter pedals were also used on the Kickr training. If that is not the case, there is an immediate question about how well the Kickr aligns with the pedals (and hence the alignment with the P bike).

  • This is a great question. I and many others recommend an FTP test anytime they change equipment. Swapping from a spin bike to a trainer can be a massive difference in feel and function. As such, an immediate FTP test is warranted.

  • If a new FTP test was not done at the time of the trainer swap, using the prior FTP may well be a mistake and lead to sub-par training. No idea if it would be too hard or too easy, but it is very likely different at the very least.

  • So, this is another point to consider in the overall picture here, in addition to all the important training related questions that Brian touches on above.

There are more questions here than answers, and I just see way more potential for influences from things other than ERG to be at the root cause(s) here.




I don’t think this is controversial but: it doesn’t matter.

It’s hard when you’re analytical problem solver by nature, but unless you are dramatically slower outside, then nothing is medically wrong with you. 100W is not tinkering with gearing or some minor detail, not even a difference in algorithms - it’s a world apart it will be some config or setting like having your weight set in kg instead of lbs, something like that but obviously not that (I have no idea how Peloton calculates FTP).

But it doesn’t matter.

Whatever number you get on your ramp test sets you up for training on that set up appropriately. And you can retest next weekend, do a 20min test or a 1hr TT if you like, to really get a sense of this quasi-threshold value. :slight_smile:


Every time I’ve changed gear my number has changed. That number is only to anchor my training to and not a comment on my worth as a human being. If it had gone up would you still have posted a question?

Interesting point would be how you tested your FTP on the peleton bike and how that matched your pedals but that no longer matters as you’re not using it. If you still have access to it try doing the same test you did before and see what the result is now. Otherwise just accept your new number or you can adjust it manually if its way too low.

If you need to justify it to yourself you may have lost some of that 100 due to being ill and some of it due to equipment change. Don’t think you’ll ever be able to get it exact as I think you’re trying to compare apples to oranges.

Good way to tell if the new number is accurate do a threshold workout and see how you feel.

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Yup, that’s exactly my thought process. What you’re saying also makes sense.

Interesting! Can you say more about this?

Short answer:

  • VO2 workouts are often considered “best” when the upper limit is set by the rider directly in the moment, vs some predetermined power level as a percentage of FTP.
  • This is why Resistance or Standard mode and actual bike shifting are recommended vs ERG which sets & caps the effort.

Plenty more reading to be had on existing topics:


Even better, turn off erg completely and use sim mode with RGT/Zwift/etc. Or do your intervals outside. Vary your cadence. Ride your bike inside as much as possible like you ride outside. I’m not saying that is a popular opinion, but has been so much better for my fitness and performance.

I think we’re focusing a bit too much on the numbers, which is my fault. I’m not obsessing about small differences. But a 30% decrease warrants at least a question.

This might be it, actually:

But my main motivation for this thread was to understand what if any impact ERG has on AT. And I’m already learning new stuff! Thanks, everybody! So I’m gonna keep the floor open for anybody who wants to add anything else.

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Most of us don’t think it is a real 30% difference. I am fairly that certain you have too many differences in variables to make a proper comparison.

If you can define the exact conditions of both tests in great detail, that will help discover if the comparison is valid or totally misleading.

  • Equipment (bike in use, trainer mode, trainer gearing)
  • Power data used (power meter, trainer, P bike)
  • Test Procedure (Ramp test, 20 min, etc.)
  • Environment (room temp, humidity, fans, etc.)

Those are the quick ones the come to mind. List all of that info for both tests, and we may have a point to start with. The info shared already points to the likelihood that we have apples & oranges in tests here.

  • And to this point, not a single person thinks ERG is the root cause / issue here. There are far more likely causes that we have already pointed to that warrant a deeper look.
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Makes a ton of sense. I’m more of a sprinter and VO2max workouts have always felt too easy in ERG.

That’s very fair! A lot has changed. P bike is not super accurate, easily could have been up to 10% off, which at 300 means 30 whole watts. And for my most recent ramp test I’m still not fully recovered from the cold, so that could be another 30w of difference easily. My fitness has been slowly declining since June because my volume dropped, I moved to another state, lots of stress associated with it, and I haven’t had a proper off-season for over two years. I think we can safely retire this portion of the thread. :slight_smile:

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So, let me try to repeat what I’ve heard so far to make sure I understand:

  1. The signal that lets the AT know whether the workout was too easy for me is the survey response. So if I answer “easy”, AT will adapt my plan accordingly. By the way, do we know if AT takes HR into account to measure effort? Or is it relying solely on my survey response?

  2. If the workout feels too easy, I can increase the intensity, and AT will take that into account and adapt my plan accordingly.

  3. Turning ERG off and riding above the prescribed power is not going to be treated by AT as the signal to adapt my plan.

More or less accurate?

  • Correct, AT looks at the power you produced, compared to the targets, and then combines your survey response to determine what if any adaptations to apply to your future workouts.
  • AFAIK, HR is ignored… see #1 above.
  • Consider that using ERG with manual adjustment to the Workout Intensity setting will allow deviation from the default power targets… is essentially identical to doing the workout in RES or STD mode and exceeding the targets to the same power level…
  • Exceeding the power targets by ANY means can work, but has limits to the impact… see #2 above.

This whole support section is worth a look and handles a number of FAQ’s to at least an introductory sense. Anything beyond that may benefit from an email directly to TR to review.