Im just an old guy that is struggling with technology I guess…being 1 watt short of my target no matter how much more effort I put into it, while trivial and meaningless in the big scheme of things, is hard to swallow…I feel that I failed the interval…
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First, and perhaps most importantly - being one watt short is not a failure of an interval.
Second - you’ll sometimes be over or under the target for an interval with a smart trainer. This is just the nature of how the trainer has been adjusting your power as well as your consistency. It really just depends and varies based on who you are as a rider as well at the latency in the trainer response over time. For shorter intervals you might even see differences of 3-5 watts!!! This also doesn’t matter at all
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When you were using a standard (dumb) trainer, did you “adjust” your effort by chasing the little ball showing the average power for the interval and the vertical line showing the target?
I would just try and stay a few watts above the target when I used virtualpower
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All the tools involved have an error of 1.5-3%. If you are within 3% of the target… you’re fine.
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Also have to take into consideration the accuracy of the device the app is measuring power from. Though thinking about this probably won’t ease your mind about the whole situation…
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I’m going to try and be more specific in my question.
If I am using ERG with a power meter in powermatch, what does this setting in TR actually do?
Does it average the reported power number in a workout? Does it smooth the power chart? Both?
It smooths the live power display during the workout. It has no affect on Powermatch or the recorded data.
Basically correct. Power smoothing setting is for the number displayed in upper left.
(not wanting to confuse, but for completeness there is also some “visual smoothing” on the graph although post-ride if you zoom in closely then you can clearly see 1 sec power data).
PowerMatch is making adjustments to trainer resistance every 10 seconds. There is a support article with details.
“Smoothing” on either the Kickr or TR app have no impact on PowerMatch.
In my opinion, smoothing is useful when using resistance mode or outside on the road. Or after the ride, if you want to get a general idea of power output over the course of the ride/workout.
For example in Golden Cheetah you can control “visual smoothing” as shown below for an outside ride:
Smooth = 14
Smooth = 100
It is a lot easier to see power output trends when smoothing is increased from 14 to 100. But it doesn’t change the recorded data, its just a visual display setting.
For reference, here are two other views of the same power data:
TrainerRoad
Strava
Just curious, is the TrainerRoad data that you present from a pedal based power meter?
power from Stages LR crank based pm
I’m really trying to get my arms around what this is. So, don’t worry about confusing me 
I’d rather dig in so that I understand it better.
I’m only concerned with what is going on inside TR workouts. I haven’t really noticed any changes when I change the power smoothing settings within the TR app, especially to the yellow power line. To me it looks the same whether I have power smoothing turned off, or set to 5 seconds. That’s why I was wondering if the charting was left untouched, but the presented number was averaged only. Maybe I need to do a few tests with larger changes to the setting.
In TR app, my understanding is that power smoothing is suppose to average the data that appears in POWER field (upper left in your screenshot). My Garmin Edge 520 has same capability, and one of my data pages has 1 second and 10 second power.
Re: does it work in TR app? Inconclusive. I’ve run TR app at same time as Edge 520, with both set to 10 seconds, and they didn’t match. After the workout the power charts match. But I just looked and somehow TR app is now set to 5 seconds (my bad). So not sure if its working as intended or not. I don’t find power averaging useful in Erg mode, so its not something I’ve paid much attention.
Re: charting in general. As you might guess, charting in general (beyond just TR app) has challenges based on the resolution of your display and the size of the chart. Thats why I mentioned “visual smoothing” as its easy to conflate the TR and Kickr app settings with the various charts you see. On the TR app, using my iPhone 7 to record a workout, the two live charts clearly look different as a result of “visual smoothing” required to display the two different size charts, each with its own time scale.
Yes, I never use power smoothing for my Kickr.
Turned mine off today before doing the workout. It’s been on since I bought my Snap 3 years ago as I didn’t even know about it. (took me a couple of minutes to even find it). I didn’t notice any difference in my workout today, but it was an easy one (Beech) so hard to tell. The numbers looked okay to me.
Also, if you’re thinking that coming up 1 watt short is failing, then I’ve been failing for a long time. 
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Ok, here is my experiment. I made a small ramp test starting at 40% and ramped 10% every 30 secs up to FTP. In the first test I set power smoothing to 0 seconds in the TR app and in the second test I set it to 30 secs (the max). Kickr power smoothing was turned off in both tests. I used Stages Gen 2 Left power meter in powermatch on a Kickr18.
Test One (0 sec power smoothing)
Zoomed into one of the 30 sec segments
Test Two (30 secs power smoothing)
Zoomed into one of the 30 sec segments
I can’t really tell any difference in the way that the power is charted. I don’t think power smoothing makes any difference here. The number being reported on screen did seem a bit more stable in the 30 sec smoothing test, but honestly it was minimal.
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Correct, as stated above power smoothing is only about the power NUMBER being displayed (and not power charting).
I’ll go out on a limb and say the typical use case for “power smoothing” is someone NOT using Erg mode - where the goal is to make power NUMBER match the target power of the interval. Because power changes rapidly up and down (even in erg mode), having a 5 second average being displayed makes it easier for non-Erg users to avoid “chasing” a rapidly changing 1 sec power number.
In other words, during a non-Erg workout the goal is getting the POWER and TARGET numbers to match (and NOT making a perfect graph).
This is the same reason I have 10 second power on my head unit when doing intervals outside - I can glance down at 10 sec average power and not chase a rapidly changing up/down power number.
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I have a Gen 1 Kickr and turning power smoothing off is apparently not an option (option doesn’t appear in app). I believe I read where it is only available for Gen 2 and above.
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