One question we see popping up regularly from Zwifters goes something like this:
“I just upgraded from my Wahoo KICKR Snap to (insert non-Wahoo trainer model here). I’ve noticed my power in workouts is must more sporadic now, bouncing up and down but never staying on the target power. Is there a problem with my new trainer?”
Or some sort of reverse version has also been seen:
“I just upgraded my trainer from (insert non-Wahoo trainer model here) to a Wahoo KICKR. I’ve noticed that the KICKR’s power in workouts is nice and steady. Super impressed.”
So what’s actually happening here? Let’s dive in…
Intro To Wahoo’s “Erg Mode Power Smoothing” Feature
Wahoo’s smart trainers include a feature called “Erg Mode Power Smoothing” which is automatically enabled out of the box. It can be toggled off and on easily via the Wahoo app:
What does this feature do? According to Wahoo’s support page, “this setting enables smoothing reported power to eliminate small inconsistencies in pedal strokes, making power graphs appear less erratic. Enabling is a personal preference, will not impact overall trainer functionality, and is not required.”
About Power Smoothing
Power “smoothing” refers to displaying or reporting your average power vs your instantaneous power. You might set your bike computer to display a moving 3-second power average, for example, instead of instantaneous. Bike computers typically offer a wide range of options from 3 seconds up to 20 minutes.
This averaging or “smoothing” results in less of the spiky power numbers which naturally occur due to an uneven pedal stroke, power readings being taken at varying places in the pedal stroke, and generally less-than-rock-steady pedaling behavior.
Smoothing is a feature found in essentially all devices and software which display cycling power. Zwift, for example, lets you choose between “3 sec” and “Instant” power in the main settings menu.
The crucial thing to understand about power smoothing on a display device is that it doesn’t affect your recorded power numbers. It just affects their display as you ride. But that’s not the case with Wahoo’s power smoothing.
Here’s Shane Miller with a quick visual description of what Wahoo’s Erg Mode Power Smoothing does to your workout data:
More On “Erg Mode Power Smoothing”
Wahoo’s Erg Mode Power Smoothing feature is toggled on and off on the trainer itself, so it actually changes the power numbers sent to Zwift (or any other device). That’s right: it’s not just changing the way your numbers appear. It’s actually changing the way your trainer reports power.
There’s a case to be made that enabling this feature is a good thing, which of course is why Wahoo enables it by default. It keeps your on-screen power numbers nice and steady, making it appear as though you’re holding rock-steady power in your workout intervals. It feels clean and accurate.
Workout Graphs Without Erg Mode Power Smoothing
On the other hand, enabling the feature means your trainer isn’t reporting instantaneous power accurately to Zwift. And that can be a bit annoying, especially if you’re a data nerd (and many of us are).
Workout Graphs With Erg Mode Power Smoothing
We aren’t sure how exactly Wahoo’s power smoothing feature works. Is it as simple as reporting, say, 5s average power? Perhaps.
But my main goal today was to shed some light on Wahoo’s Erg Mode Power Smoothing option, so people can disable it if desired. And I wanted to put you at ease if you’ve noticed your power looks more erratic now that you’re on a trainer without this feature. Don’t worry – as long as your trainers are accurate, you’re doing the same work as before. It just may not look as “smooth”.
Questions or Comments?
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I guess that does not change the values transmitted to zwift when e racing, even if ON, because in racing we are not in erg mode ?
If you did race with erg – you would lose some of the spikes and I would think that average is not the best for the racer. But its avg so its not going to raise your power.
my power in workouts is much more sporadic now,
This “feature” hides the pedalling issues (non smooth pedaling style, “kicking”) at the rider and wont be efficient outside neither. I think it is the worst thing what the Wahoo could do (but from their POV, it is a good thing, due to “non-erratic” power values -> happy customers -> more sales… )
I’m not sure it necessarily hides a non-smooth pedaling style (if by that you mean the distribution within a single revolution). I assume it reports power every one second, which seems to be the standard for .fit/.tcx/.gpx/etc files. Since most people already spin faster than that (>60rpm), the value it reports “without” smoothing is already averaged across at least one pedal revolution if not ~1.5.
I avoid training with. ERGI, I prefer to feel the gear changes and explore my maximum power. today I trained with Brevet like this:
When it comes to maximal sprints, being out of ERG is a good option for sure.
But if I need to hold X watts for 5 minutes… I’d rather the system just does it for me. To each his own.
Purists. Sheesh.
That aside, building on what Cam asked, because it wouldn’t be the first time a poor choice of nomenclature led to confusion…are we certain there is no impact on Free Ride and non-ERG workouts if this is toggled on?
Thx
Yes, we’re sure!
I did FTP test yesterday on my Kickr V4. “Erg Mode Power Smoothing” was toggled ON in Wahoo app. Zwift is reporting erratic power spikes. 100 watts over/under is not unusual. Same disaster during races. Spin down doesn’t remedy this issue. This is an ongoing issue for number of years now, where training/racing with ERG mode off. I think the only solution is to upgrade to Kickr bike.
I don’t seem to have the toggle option for power smoothing in my version of the Wahoo app. I’m using iPhone and gen 1 kickr. Do I need to do any additional set up or enable other options to access it?
It’s all designed on hysteresis – you still have to “average” the correct power for it to report that target, or it will eventually ding you. You can slow your cadence and speed your cadence up, and it will dynamically adjust your resistance to make sure you are putting down the power until you physically can’t. In other words, if you are having a lazy mindblock day, and aren’t shifting as much as you probably should, it might be best to leave it on to get the gold star. If you frequently get out of the saddle, the same concept applies, where you might inadvertently dump a lot more watts during a short recovery effort. The numerics still work out (watts over time), but the pedaling dynamic can differ significantly with ERG Mode Smoothing on versus off. On my KICKR Bike, I pick my battles with it – sometimes I want the realism of variability – other times (especially during “social” workouts like with USA Triathlon), I turn it on because while I’m there to workout, I’m also focusing on the conversation experience to conceal the pain.
The best use-case I have for ERG Mode Smoothing when doing “solo” workouts are those days where I might use a custom workout for something like Alpe du Zwift, where I just want to hold whatever W/kg target over a specified time duration, and am not worried as much about the gradient feel as I am to complete training zone targets during a certain period of time – to not lose power when it flattens out, and to not gain power when it gets steeper.
What you’re describing is ERG mode itself, not the power smoothing Wahoo applies to ERG mode.
Do wheel-on trainers generally report smoother power than direct-drive? I got very smooth readings with ERG workouts on my old Tacx Vortex Smart, but when I got a Neo 2, I thought ERG wasn’t working because the power numbers during ERG workouts was so jumpy. (I got used to it quickly.)
Does the Elite power smoothing work in the same way? It’s not a toggle
on/off but a value setting between 1 and 10. The Elite setting doesn’t mention ERG mode either so I assume it applies to all rides?
Hi Eric / Zwifter’s… was on a group ride today and many of the riders were talking about their average watts so far through the ride. I can see my actual power, and my w/kg as I ride, but can’t figure out how to see it on an average basis until the end (either in watts or w/kg)… I run a KICKR Smart Trainer (6 months old) with Zwift on Mac… any ideas?
The only way I could do it was using the power meter on my pedals and then having my garmin computer screen showing the averages. Yes, I’m still pretty new to all this, so the techno jargon is bad. Lol
You can also do this: https://zwiftinsider.com/wahoo-erg-mode-power-smoothing/#comment-85341
Having it off let’s you see how poorly the KICKR bike is at giving the necessary resistance for the required watts, at least compared to my Neo 2T (and I have a very smooth cadence!) I don’t know what the case to be made here is; it seems to serve no useful purpose…
The Erg Mode Power Smoothing function seems to come and go from the Wahoo app (Android), not sure why. I think it’s only there if you start pedalling in a workout, but I’ve not tested that thoroughly.
I switched erg mode power smoothing off, and I much prefer the instantaneous feel. But I now often get far few xp for segments in workouts, and often the stars aren’t full, despite doing exactly the same as before. I used to get full stars always unless I ran out of power and blew up.
Even when I get a full star I often get less xp than previously. For example, my warmup starts wtih 3 minutes at 70w, and I normally get 30 or so xp. This morning I got 7xp and a full star. Any ideas what is going on?
Having power smoothing on or off shouldn’t affect the feel of the trainer at all – it just affects the numbers the trainer sends back to Zwift. As long as you keep pedaling smoothly it should keep you close to the wattage target and give you a full star.
As for the XP thing… it’s possible Zwift changed how XP works for workouts. But as far as I know, they haven’t! (See https://zwiftinsider.com/xp-for-cycling-workouts/)
I should note that this suddenly got better a month or two ago, with no change on my part. So, whatever was going on, no longer is, and it’s all fine now. Remembered today as I was warming up and thought I should note it.
I feel like my pedalling in trainer is harder than outdoor ride. I’m using wahoo kicker direct drive.
why is it?