ERG mode for VO2 max intervals?

Just started using a Saris H3 after 9 years of using TR with dumb trainers. The H3 is supposed to have one of the best ERG responses but with 30 sec V02 max intervals it hits super hard a few seconds before the interval starts but the power doesnt catch up for over 5 seconds…then it over shoots and suddenly you are spinning at 140 rpm…then it levels off, then when the interval is over you are spinning at 140 with no resistance. Is this normal? I ended up using resistance mode after the first set and it seemed easier to hit the targets and manage the rest periods.

Seems like an easy solution - don’t do 30” VO2 Max intervals.



I have the H3 as well. MOST of the time it works well but when it doesn’t it drives me crazy. I have experienced similar issues. Like you, sometimes there’s a delay (mine has been up to 10 sec). Everything going well, then an interval runs long or short. Then the interval starts later. It seems to do better on the longer intervals than something like 30-30s. It doesn’t happen all the time but when it does is quite annoying.

Another issue I have experienced is sometimes I need to hit high rpm’s for the erg to kick on. Also getting some plastically creaking sounds that seem to pop up later in the workout.

I got it on the super sale so I guess you get what you pay for.


I would argue that 30s intervals are not vo2 max but thats besides the point.

For any vo2 max intervals I dont use erg as they are supposed to be maximal and set % of FTP does not really work across everyone for power >FTP.
I would do them in resistance mode and pace as hard as you can while maintaining the same watts throughout the interval and across them.

Ignoring the iLevels stuff you can see here that there is significant variation in PDC at shorter efforts.

I would also aim for higher cadence efforts at the expense of maximal power but thats another topic that has been covered here.


If the trainer is in ERG mode it only will fluctuate 5-10 watts either way of the target, you cant set it up for power zones unless you ride in resistance mode…

Is there a power smoothing setting on your trainer that you can disable? When you say it hits super hard but the power doesn’t catch up, it sounds like it is the power being displayed is just lagged - if you feel it in your legs, you must be doing it even if it doesn’t display that way.

Do you get the same behavior on longer intervals on ERG mode? The trainer doesn’t know it is a 30 second interval, so it seems like that should happen every time regardless of interval length. Maybe it is just more evident with the higher power demand of a short interval?

Edited to add: perhaps email TR support just to see if they have any suggestions.

This is from my VO2max workout last night. I’m on a Saris H3 in ERG.

You can see some of the issues; one “high” power section bled over into a “low” power section in the first set. Opposite happened in the second set. Most of the power changes between the high and low sections are a bit messy as well.

But this was also an effective workout which, overall, hit the targets and did what the workout was intended to do. I’m happy with using ERG with the H3


It might help to see the workout in question here, specifically including power and cadence. A link to your workout if you TR account is Public is great, but a zoomed in screenshot can be workable too.

For reference, here is my latest workout of this type, 30/15 VO2.

This is with my Kickr V3, but I had similar results back when I was using my Saris H2. Essentially the same trainer as yours other than the drive belt and pulley.

As ever, cadence is key in ERG workouts, and possibly more important in these types of efforts. It can be tougher to handle the changes, but you need to get to and hold your desired cadence as steady as possible.

Also, gearing can impact results. Trainers perform best in moderate gearing as opposed to higher gearing. Using the small ring and middle of the cassette is best WRT trainer action. I use the 34t x 17t and the trainers all respond quickly and predictably.

Generally speaking for this type of effort:

  • I roll in about 5-15rpm lower cadence than I aim to use for the work intervals.
  • I kick up cadence right as the interval timer hits the start. This is 1-2 seconds after the trainer actually gets to upping the resistance level, since TR sends that instruction about 2 seconds early on purpose (to handle trainer adjustment lag).
  • Once in the early seconds of the interval, I try to stabilize at my desired cadence and then hold as steady as possible until the end.
  • At the end, I slowly reduce cadence against the faster spinning flywheel and lighter resistance, and then ready myself to repeat it all.

As you can see above, even with as short as a 15s recovery, I am hitting the power targets (more so the trainer) with some peaks in the process as I am kicking up the cadence. Other than that, it is predictable and holds targets as desired.

For those that want to, swapping to Resistance or Standard mode is an option and one that might make more sense. But it is possible to rip these workouts in ERG if that is the preference.


This wont show much because after the first three warm ups I switched to resistance mode. I felt pretty good yesterday and I think I may have under tested on last weeks ramp test because the target of 260 watts felt like tempo work so I decided to see what I could do.

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Yeah, it’s hard to offer much with so little time in ERG. But from the minimal bit I can see, you may not be holding steady cadence. Seems you are potentially ramping up your cadence all thru the short interval. Maybe a more zoomed in view of those 3 intervals would show different, so it’s hard to offer more than what I already shared above.


  • ERG is a different beast than other modes and cadence is king. It takes a bit of time and effort to place the Resistance mode skills to the side and focus on what ERG needs. This short-term effort was not really what I consider enough time to get used to it.
  • That heads down a very different road of VO2 max and how it relates to Threshold and the like, as well as the whole “short stuff ain’t VO2 max…” which can be seen in many other topics.

I will give it another chance in upcoming workouts. Thanks for the input.


Can I ask what workout this is? Tried looking it up and oddly your Katahdin -2 is different than the one showing up in my workout list. :thinking:

It’s Katahdin -2

In the screenshot I have zoomed in to show the first two blocks in detail. Maybe that’s why it looks different? :man_shrugging:

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That’s probably it… missed the zoom in.

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I’d prefer to do VO2max or higher effort on resistance. Just go as hard as I can for the prescribed time. Love erg for sweet spot and threshold. Endurance I like erg if I’m watching a movie or bike race. But also like to off erg on some endurance just to be able to mix it up.


I bought the same trainer on a deep discount. Erg mode took some getting used to after years on a dumb trainer. When I initially set it up, I was using Favero power pedals as well that I figured out were reading wrong (broken right pedal), which really messed with the resistance. The best results I’ve had for doing 30/30-type intervals is to:
-get cadence where you want it for the interval BEFORE you start it. (even just 3-5 seconds prior)
-use the little ring in the middle of the cassette for a straight chain line. This is imperative. You basically just don’t wind up the trainer as much so it’s more responsive for short intervals.
-offset the 5-10 second delay in power getting to where it’s supposed to be by adjusting the workout intensity a couple/few percentage points.
I definitely switch between erg and resistance mode as well, just because I think it’s good to dial in your power somewhat manually from time to time.
Hope that helps!

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Its possible you didn’t undertest and that FTP will be spot on for Endurance, tempo, SS and Threshold (although ERG doesn’t suit some folk either). Your actual oxygen based VO2max zone perhaps lies outside the predicted power based VO2max zone for the average athlete. There’s some good podcasts on the subject, I like this one:

Watts Doc #23: Training Your VO2max, and Why Not Rønnestad 30/15 Intervals - Empirical Cycling


VO2 max intervals have very little do with FTP.

Yes, you can use FTP to get your body up VO2, but it just a mechanism to get to the target, FTP isn’t the target, VO2 max is!
Once at VO2 max, maintaining FTP isn’t possible, FTP will fall and that is ok, its normal, despite your body’s attempt to stay at max.
If that isn’t what you have experienced in the past, you haven’t experienced VO2 max. More likely Threshold.

Increasingly, the research is recommending, doing very high, very short intervals, but lots of them. Eg 6 sets of 15 repeats of 10sec + 10 sec recovery, with passive recovery of 3-5 minutes between sets. Such short sets really need a time keeper, essentially a coach, but 20sec/20sec are feasible using TR apps. Current research is leaning towards 30/30 being considered long, the top end of VO2.

This is very different from much of the traditional VO2 workouts, many of which remain as part of TR.

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I am not saying that they do, quite the opposite. I completely agree that you should be targeting VO2 max rather than a set % of FTP which is why I recommended to do them as a maximal effort that is sustainable through each interval and across each set (and at a high cadence).

As for shorter Rønnestad 30/15 style efforts I would listen to the post directly above yours on why they might not be the best direction if your targeting VO2 max improvements.

This thread is about ERG mode use and application for VO2 intervals. Please move discussion about the essence of what is or isn’t a VO2 effort to one of the many existing ones essence.