10 second power averages on biking workout

Also, the reason that my power fluctuates this much, is my left leg is not as strong as my right leg. My power is 60% from right and 40% from left. When I ride with a cadence of 90, in three seconds, I get in two left pedal strokes and one right pedal stroke, or vice versa. That means the power in 3 seconds changes from 40-60-40 to 60-40-60 a difference of 20. So the power output fluctuates between 140 and 160, just from the way the power is measured and averaged. Three seconds is just to little time for things to average out enough.

Hi, I think there's quite a bit to unpack here. First up, what power meter gave you the 40/60 L/R balance, and have you done any tests to verify that those readings are correct? (I'm personally very interested in this topic because I have a 60/40 L/R balance under most conditions, and I think I've done enough testing on the power meter itself to satisfy that it's reading correctly).

Also which Garmin watch is this?

Second, are these workouts on an indoor trainer? Is ERG mode on? Is the Garmin watch controlling the trainer? Or are these outdoor on open road? Or maybe in a velodrome? Power data is notoriously noisy (even with averaging), and outdoor conditions will be far harder to hold steady than a flywheel-equipped trainer in ERG mode.

Next, I understand what you're getting at with the L/R imbalance affecting the averages (though I never thought about it that way myself), but I think the math is a bit off. The 90 rpm cadence is 1.5 revs per second, so 3 seconds would give 4.5 revs. That's effectively 4 strokes on one pedal and 5 strokes on the other, so over 3 seconds it would drift from 440 to 460 (or vice versa), using your 40/60 numbers. With an average of 450, that variance of 20 is only about +/-2%, and it's drawn out over a full cycle of about 6 seconds. That's approaching the accuracy level of many power meters (and indoor trainers). And I believe it's also considerably less than the natural variations that occur when outdoors on open road. So all that to say, although a L/R imbalance might surface in the power values you're seeing, I suspect it's not as significant a contributor to the fluctuations as you suggested.

Personally I don't use averaging ever. On the Garmin Edge, and in apps (Zwift), everything is set to 1 second. Yes it makes for noisy power data, but it's how I prefer it. Averaging also introduces a lag that can also result in rider-induced oscillations, as I chase "stale" power values. So it has pros/cons whether to use it or not, it's a personal decision for sure.

Anyhow I realize that doesn't immediately address the question about 10-second averaging for workouts, but I think it's important to first verify the setup to make sure an underlying problem isn't being missed here. Hopefully your answers will point to a simple solution. Cheers

The power meters that give me 60-40 are an 4iiii precision pro dual sided on my previous road bike and an Assioma duo on my current road bike. Both give the same numbers. The Garmin watch is a 945. These are workouts on the open road, in wind and (very minor) hills. Also due to my left leg has problems (lots of things here, but I am working on it with doctors and fysio) , the 60-40, it is something I do expect to find.   

I agree with the math. My bad. sorry for that. I was looking for an explanation to hard. 

I mostly use my power on longer rides, and would like a little warning when my mind wanders from the power output I am suppost to do and I the start taking it easier automatically. 

I like it when I have intervals I dont have to remember where I am and what power I have to do. I find it very hard to remember stuff when my heart rate is over 150. Also that is why I bought a tool.  

If you want average power different than what is available on your device, check out the Connect IQ store for Data Fields app offering it. Mostly they not only show it live on the device, but also record a graph for the later review in Garmin Connect.

I just checked the store for some links that you can look at (see below). I did not test or study any of them, so cannot tell which of them offer the 10s average. Should you not find any such app, do not hesitate to contact the authors - some of them will be certainly willing to add it to their app.

• Power Graph | Garmin Connect IQ
• MeanMaxPowerChart | Garmin Connect IQ
• Average power field | Garmin Connect IQ
• Moving average power field | Garmin Connect IQ
• Average Power Zone | Garmin Connect IQ
• AVG power field | Garmin Connect IQ
• ... and there are certainly some more of them in the store

Tbh my math is probably wrong too lol, I don't feel like whipping out Excel today

Okay it's hard to argue with 2 different dual-sided power meters, so I guess that's good news that it's not a hardware mis-reading. Unfortunate that it's an actual "imbalance" though, I can definitely relate to that!

The reality of power fluctuations in outdoor rides still makes narrow power targets difficult. One option might be to simply widen the Workout power target range Garmin Connect. It would have similar affect to using a longer average. 

You could also just disable Workout target alerts, but I guess that defeats the purpose.

I'm struggling to find any options to set workout targets to anything other than 3s avg power. Closest mention I found was this old thread that says that although Garmin Connect defaults to 3s avg when building the workout, the workout can be edited on an Edge device (so maybe watches too?) to use 10s or 30s avg. I tried it on my Edge 530 and can't find any such option however. Maybe aweatherall can help regarding his answer in that thread.

If your watch has them like the Edges do, there are also non-Workout power alerts that can be set for min and/or max values (or zones?). But fluctuations would still be an issue, so would still need a relatively wide power band.

There might also be Connect IQ apps or other 3rd-party options to make Workouts differently, or a non-Workout option, but I don't know personally. Hopefully someone else has more ideas.

I agree, removing the alert does lessen the functionality of the tool I bought.

On the watch In the workout I have no options to edit. Just do workout - view - and delete. ( I found that thread too ;) 

I tried editing the fit files created by my Garmin training plan in folder -Interal Storage - GARMIN- Workouts - Schedule. Because I found https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-6-series/301169/setting-alerts-for-10-second-average-power-for-workouts But the CSV tool in FIT CSV Tool | FIT SDK | Garmin Developers does not import (encode) the files, when I export (decode) them and do not change them in any way and then immediately try to re-import (encode) them. (errors and gives a message cannot encode this number of rows.)

 I do not have the skillset to create a fit file editor, and using the CSV tool already was more due diligence than me being willing to do that on a regular base. (once for all the workouts in the training plan would have been be an evening well spent though) 

What I did find though that everybody complains about it, but eventually accepts that there is no solution. 

your math is quite correct. I just don't get your 6 seconds remark, I assumed a rolling average of three seconds. A delta top to bottom of 4% relates to an about 8 watts fluctuation at 200W, the fluctuation induced from this would be 196W to 204W. a bit annoying but when seen against the range (170W to 220W) It would be alright. But it does take a fairly sizeable chunk of  16% out of the available range of the zone in the zone.

I am using a Garmin Training plan. Will these accept input from a Garmin training plan? The 10s average zone is natively available in my watch. I just cannot use it to program a workout. Also when the Garmin Training plan generates a workout, it also uses the 3s average.

7672294 said:

your math is quite correct. I just don't get your 6 seconds remark

Actually I now realize that none of our math is correct lol. We can ignore the "6 seconds" and the entire thought exercise we started with as I believe it's flawed, since we weren't accounting for how power meters work.

The TL;DR is that a steady L/R imbalance will not have any affect at all on displayed power fluctuations.

Basically the power meter needs a full cycle to calculate the total power, and the value it transmits is that total power from a complete cycle. It's never sending a value that is some mix of partial cycles or left/right strokes --- it would never work if it did. So regardless of a rider's L/R balance, the full power from a complete cycle is still always sent. (Then, unrelated, the receiving device records it at 1 second intervals, at most, for Garmin devices with "smart recording" turned OFF.)

So all that to say we're simply left in the realm of power measurements being challenging and noisy ("spikey"), much moreso outdoors, and so it's difficult to stay completely within a narrow target band.

In the absence of Garmin letting us access the other workout target power options that FIT files support (10s, 30s, or lap avg power), I still think there are only 3 options available, pros/cons vary:

A) Set wider target bands. For example instead of 150-170 W, widen it to 140-180 W. It'll have similar effect to using a longer averaging period, and should reduce the number of off-target alerts (but probably not all).

B) Use the Range Alerts feature instead of a Workout. More limited capability than Workouts, but may have more control over disabling alerts.

C) Use a 3rd-party workout builder (Connect IQ, app, or website) that has the 10s avg option, and import the workout to Garmin. I'm not familiar with any personally, but I've seen web mentions of bringing in workouts from other sites/apps.

Hope that helps! Oh and of course it doesn't hurt to contact Garmin Support directly to bug them about the missing options. (Actually after some searching I get the impression that Workouts originally used instantaneous power only, and Garmin changed it to 3s avg power after user feedback. They really need to just add all the options though instead of only their default.)