Kickr TSS vs target TSS

Can somebody explain why it is nigh impossible for my Kickr to hold the targeted power?
Let me explain.-
A workout in ERG mode will give me a target (for example) of 200 watts but the Kickr keeps me at 199 watts. This results in the actual TSS being adrift of the target TSS.
Today I tried increasing the power on my app so that it corresponded with the target. But still the resulting TSS was below the target.
Can anybody help me understand why?

In ERG mode a trainer (any trainer) is trying to dynamically adjust things such that the power you are producing is the target. This is imperfect, because your cycling is imperfect. From pedal stroke to pedal stroke there may be subtle differences or even large differences so the power can swing around and not be precisely the given target for the interval at all times.

That being said, how much of a difference are you talking about?

Thanks for your input. It seems to be constantly 1 watt under.
To put this into perspective. Yesterday I did 90 mins L2 where it constantly showed this -1 watt. The target TSS for the workout was 83 my result 71
Today, I adjusted the app power upwards to come into line with the target power throughout the entire workout and yet the result was still 3 points below the target.
I’ts mystifying…and yes I calibrate the kickr.

There must be something else awry here as a 1 watt difference would have little to no impact (as in less than one) on your TSS over that duration. For example, I just calculated TSS for 90 minutes at FTP and riding 1 watt below makes a 1 TSS score difference and I’d guess your target was actually below FTP which would make the impact smaller.

Which apps did you see the target of 83 and result of 71 in for TSS? It’s worth double checking they both have the same FTP set.

FWIW to go from a 83 target for 90 minutes to 71, and assuming a 200w target, you’d need to be down to 187w (this is assuming steady effort for the whole workout ie no intervals)

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Thanks for the excellent input.
Let me first say I’ve noticed this discrepancy over several years with various apps. The two main apps I use are “Perfpro” and “IcTrainer”. In yesterday’s and today’s case the workouts were downloaded from Atheletica.ie, but this has happened with everything from Sufferfest to Trainerroad and others. It happens even when I produce a workout in IcTrainer to use in IcTrainer. This is what I am finding so strange.
Attaching the results, and as you will see they don’t correspond with what I was actually doing, that is to say, following the power exactly.

Out of interest, what gear are you in when you do ERG? Ideally you’ll want to be in the small chain ring and roughly mid cassette as you’ll find trainer accuracy increases with lower flywheel speeds.

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Agree discrepancy in ftp setting seems most likely culprit. FTP setting is what’s used to “weight” the power to get TSS

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Big ring and mid cassette normally.
I’ll try that tomorrow.

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FTP is identical in both apps. New FTP test on Thursday but most of that will be done in SIM mode so should be more accurate I would think.

Got it, okay I guess it depends then. I thought you were saying you were getting wildly different TSS numbers from substantively identical power, which is what I understood from your first reply, but if that’s not the case then I agree ftp setting probably not the issue.

If it’s as simple as the trainer not seeming to hold a target power, it could be a couple of things. If it’s just a few watts, it could just be about how the trainer comes up to the target and responds to small changes in cadence. The graphs that show power and cadence as perfectly uniform are usually smoothed to some degree, in reality power jumps around because of tiny (and very normal) between pedal strokes and even how/when the power meter takes a measurement. It gets exacerbated if you use power match — ie power meter to measure, but trainer set the target — because of latency in the true-up.

The good news is the differences in wattage you’re showing in your second reply — 98 vs 101 — really don’t matter. Even for a longer ride where the tss differences add up to be more substantial, it still doesn’t matter. Eg endurance: If you properly rode endurance pace—a pace you can sustain w/out finishing that much more tired than when you started—at the duration you wanted, then you did the workout right. +- 10 to 20 TSS is really irrelevant.

@devolikewhoa
Today I tried first with small ring but that didn’t work at all. I set the power on IcTrainer to 1 watt above the target and that way held the target throughout the workout…BUT even so the result showed I was 5 points under the target, but as you say perhaps as it was an L2 ride didn’t mean much but still its irritating.

No I totally get it’s irritating and I didn’t mean to sound dismissive.

If I may ask, are you using a separate pm? Or if the kickr functioning as both the trainer and the power measurement?

I’m curious about the exact 1 Watt difference, and how that’s being calculated. Do you have the Kicker Erg mode smoothing enabled ?

NB. Not the Systm X power smoothing, the Kickr one that gives those weird straight lines

I didn’t think you were dismissive @devolikewhoa, don’t worry :smiley:
Not sure what you mean by “PM”, but I’m downloading from “Athletica” and Using “IcTrainer” on W10 PC. IcTrainer is connected to the Kickr via Ant+. But it doesn’t seem to matter which apps I use it’s always 1 or more watt under. Been like this since I bought it.
But Athletica is making the comment about being under TSS target si its getting more irritating lately.

@fukawitribe , I don’t use the Wahoo app but you have given me an idea and I am just checking with the producers of IcTrainer if smoothing is built in as I can’t find that in the settings.

PM = a power meter. He was wondering if you’re transmitting power from a separate power meter and then your laptop/phone is controlling thr kickr resistance. This can lead to power mismatches and ian’t the best way to use SYSTM. Best to only use the kickr to both transmit power and be resistance controlled.

Like others, I suspect you have power smoothing turned on for the kickr. Worth turning that off and seeing if that resolves the issue. I see you dont have the Wahoo app, worth downloading it as you need it to do everything for kickr including updating Firmware and changing settings. I wonder if the Kickr is automatically on smoothing mode as default unless you turn it off. Worth checking. And then also doing a spindown calibration of the kickr in the app.

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@DameLisa, I do have the Wahoo app and check for updates and calibrate regularly, but I’ll check today and see if smoothing mode is turned on or not. I must admit, although I can’t remember if I have turned it on, I would probably done so thinking that was a good option. But obviously not in this case. Thanks for the advice.

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It’s enabled by default, and is almost universally considered A Bad Idea for training purposes. It looks ‘nice’ to some, but is significantly divorced from what you and the trainer hardware are actually doing with regard to effort (and hence the real IF/TSS etc experienced during the activity).

Yes, you are correct. I’ve just checked and it was on. Have now turned it off now. Have an FTP test tomorrow but will see how it behaves when I do another normal workout. :smiley:

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Fingera crossed this helps. Will keep an eye out for your update!

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