Failing Vo2 Max in ERG Mode


I have been struggling with failed Vo2 Max workouts triggering the “Struggle Survey” at the end.

So I reach out to support about this, which was quickly pointed out that I was not hitting the power targets which is very reasonable, and it was recommended to use resistance mode instead of ERG. I had noticed this before since it take the trainer (Elite Tuo) a couple of seconds to ramp up, and then it overshoots the interval, and then it sometimes sits bellow the power target, which I find weird.

So I came into the forum to do some research and it seems to be that some people use ERG for 30s intervals.

Now my question: Is this a behaviour of specific trainers? Are they trainers out there that do not struggle with 30s intervals. I ask because I’m looking to upgrade my wheel on Elite Tuo, to a direct drive and want to have this in mind.

Practically every trainer struggle on ERG for short VO2max intervals, just switch it off and use resistance mode.


Can you share a picture of a zoomed in section of an interval set?

  • I am betting it will show “time shift” with the trainer lag on the front, but also the back end of the intervals. The basic load is still hitting you, it just is delayed compared to the blue target blocks. That matters since the interval summary you are pointing to above will “miss” the reality of what you did.

  • That in mind, I recommend taking those with a grain of salt at the very least to ignoring them entirely. Look at the graphic to see what you are doing, not the actual numbers.


@tuxedotrainer, As @HLaB suggests, many folks here report similar issues and switch to resistance mode. That said, with my Kickr CORE in ERG, i’ve had pretty good luck, but to @mcneese.chad’s point, my results is usually a couple second ramp up at the beginning, followed by a couple second ramp down at the end, so the overall interval matches up +/- 2 watts when viewing on the web as you show above.

Given you are using a wheel on trainer, I wonder if maybe you are hitting a wattage ceiling with the current gear you have chosen? Maybe try shifting up a couple cogs and try it again in ERG mode to see if you get closer to the target wattage for the interval??

  • Yes, many trainers handle this well. Most of the 6 or so I have used all handle these well, assuming the rider handles their cadence smoothly.

Below is a shot of the first interval of Flume -2, that consists of 15/15 hits and a few with 30s recoveries.

Note how well this nails the overall goal.

I am curious to see the example of your workout, but I have never been impressed with the ERG performance of any Elite trainers. They are slower in response and take more time to stabilize than the Saris, Wahoo & Tacx trainers I have used with great success for even these very short kicks.

  • Cycleops Hammer & Saris H2, Tacx Neo2, Wahoo Kickr V3 & V6.

Either resistance or standard (my preference) mode for high power intervals like this IMO.


Hey @tuxedotrainer, I am confirming the speculations of @HLaB @mcneese.chad and @Will_Peters based on your last few VO2 Max workouts. :sweat_smile:

ERG trainers perform a brief ramp up to an interval’s target power. For longer, less-intense intervals, this ramp-up is hardly noticeable. However, this ramp is more pronounced for short, high-intensity intervals so you may want to consider riding in Resistance Mode to avoid any lag time in reaching their target watts.

Some trainers work best for these 30 second intervals when in ERG Mode, sounds like the KICKR Core would be one to consider!

Otherwise, try Resistance Mode and let us know how it goes!

If you’re interested theres more info about trainer modes here:


Such a simple problem to fix in software analytics.

1 Like

I rarely dive into interval analysis since a quick looks at the graph shows if I was on target.

But it seems that stuff like and others that “build” intervals by the actual power profile vs what TR does (analysis per the prescribed section only) may be superior on a number of levels.

People notice they aren’t “hitting” the numbers. But the numbers are wrong because they are offset by a second or two.


It looks something like that.


I only noticed because I kept hitting the “Struggle Survey” which I just respond “I did not struggle”, but wondered what effect it would have on AT.

You aren’t going to get perfection on the chart with erg mode. When I’ve done these intervals in ERG my chart looks more like chad’s. I rev my cadence to like 120 three seconds before and then just hold it the best I can. I don’t try to influence the power any more. I just let the trainer adjust. So, it will overshoot and then undershoot and then equalize. The average power for the interval will be close.


Broadly speaking, that looks fine to me. It is certainly not as “stable” as what I get on my trainers, but I wouldn’t call that a “fail” in any way. I would suggest ignoring the interval summary data if you want to keep using ERG mode.

But, this and other reasons are worth testing in Resistance mode or Standard mode (not present for all trainer) and see how it goes. Then pick whatever suits your preferences and move forward with that into the future until you decide to change trainers.

But I see no need to push for a different trainer based purely on this type of workout and result. You can sure move to wheel-off for the many other reasons those are preferred though.


For me, KICKR V5 works great in erg mode:

Like others have said, the actual power lags the blue bars by a second or two, so the AP for the intervals is a bit lower than target.

Same workout recorded on my Quarq. According to intervals I was doing 28/32s (not 30/30s), but they are very consistent.


That’s some impressive consistency in numbers.

Comparing this graph to your previous snippet of the data and as @mcneese.chad and others have said, you’ll never get a perfectly consistent graph, but it does look to me like you might be spending MORE time UNDER target vs over, and I wonder if this is because you are using a fairly LOW cadence (per your data page snippet).

A lower cadence in ERG mode is going to make the higher intervals feel MUCH harder (and this could possibly be where much of the variability/jagginess in your graph is coming from). If it’s within your capabilities, can you raise your cadence to 95+ to see how that works out? Even if it doesn’t get the “overall” target of the interval closer (in the data analysis), at the very least, it will make the interval FEEL easier, allow you to keep closer to the target AND maybe minimize the struggle surveys as well!

1 Like

I see your point, and I have to say this was my first interval and I have a tendency of “being lazy” and always do the first interval at lower cadence for some reason, as soon as I start to become tired I will fallback to a “normal” cadence of 90+.

But just to clarify, the struggle survey is not appearing because I struggled. I feel great during the ride, and afterwards I rate it a Moderate. It’s just that it’s auto detected by trainerroad as failing because power is under a certain threshold.

Vo2 shouldn’t be done in erg, each one should be max, power will drop off across intervals

1 Like

While I agree, that’s a different discussion. This is a TR user following TR plans, so while I disagree with their VO2 workout design/intent, I just try to stick to answering the question asked. :slight_smile: