Ramp test power mismatch in ERG mode

I just did a ramp test and found that for the last two minutes, the target power was increasing as normal, but the measured power and trainer resistance weren’t. I had TR reading power from my power2max NG (with “new” PowerMatch enabled), and I had a separate device reading power directly from my KICKR for comparison.

Here is what I recorded:

Frustratingly, my 1-minute power is exactly the same as my 2-minute power, which means this test underestimated my FTP by some unknown quantity.

The power reading from the KICKR matches the power reading from the power meter fairly well, so I don’t think the KICKR is at fault:

https://analyze.dcrainmaker.com/#/public/a598a680-4efe-4a13-4180-81632bba2958

Could this be something to do with PowerMatch?

I would reach out to the team at support@trainerroad.com so they can take a closer look at your internal ride log. :v:

A bit out there, but is there a chance you hit a wattage ceiling for your trainer and gearing?

Which exact Kickr model do you have, and what gearing were you using for the test?

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Mr. McNeese beat me to it. I would suggest the same wattage ceiling theory. :slight_smile:

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KICKR 2020. It’s about 2 months old. I think I was in 34/26 gearing (or something similar), so pretty low. If I can max out a brand new KICKR with a ramp test, what do pros do? :thinking:

Although, now that you mention gears, I think I actually changed down a gear two toward the end of the test… Yeah, I know this is pointless, but I guess it’s a reflex :man_shrugging: Maybe this could confuse PowerMatch somehow? I dunno, clutching at straws here.

OK, plenty capable trainer, but that still doesn’t mean it is capable of hitting the peak power in all gears. This is a commonly overlooked issue, so just covering bases.

I wouldn’t expect there to be a problem, but considering you are testing at a 340w FTP, you are in a realm I can’t even dream of experiencing. Since you were in a relatively low gear to start, it is entirely possible the trainer might have hit a limit.

  • No idea, but until you set an ERG target at wattage above what you hit, in the same exact gearing, and see what happens again, we simply don’t know.

As to shifting, yes, that could easily have an impact. I have not been using any PowerMatch (new or old), but it’s important to recognize that it adds another step in the power data chain, and could be making any change a bit slower in reaction.

  • The act of shifting will certainly upset the order of things in a simple sense. TR will have to respond to how PowerMatch may react to that.

  • But in a simple sense, when you shift to an easier gear in ERG, you are forcing the trainer to react and add more resistance to hold the power target, since you just made it “easier” from the downshift.

  • If you are even close to approaching limits of the trainer or PowerMatch, shifting will almost definitely make the whole power situation worse. I get the reaction, but shifting like this, in the waning moments of a test is not a good idea, IMO.

  • The only shifting that should take place in ERG use should be to adapt to wattage ceilings and floors of trainers, or for quick cadence changes as desired (for low cadence drills, standing, etc.). Otherwise, pick a gear and ride it out.

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Really thorough answer, thank you!

I’ll try setting an ERG target with similar gearing and see what happens… though I’m still a bit skeptical.

As for the shifting, I totally agree that it can only compromise the test results, but my lactate-addled, oxygen-deprived brain wasn’t functioning properly! Next time, more discipline.

Anyway, I think the shifting is quite probably the culprit in this case. If you look at the power on the DCR Analyzer page, the plateau corresponds quite closely to a drop in virtual speed – i.e., a downward gear change.

I’ll do the test again tomorrow (:tired_face:) in a fixed gear and see what happens.

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Good deal, I am interested to see what your testing shows. I’d suggest trying the absolute lowest gear you hit in the test, after shifting. That is essentially the worst case scenario I can predict for a trainer hitting it’s wattage ceiling.

Have fun testing :smiley:

I’m happy to report that this evening’s ramp test went much better!

I really really don’t enjoy ramp tests, so I wasn’t in the mood to test the low-gear theory and I played it safe by spending the whole test in 34/19 gearing (middle of the cassette).

The power and resistance behaved themselves perfectly this time, and I even hit a new PR:

Still, I’ll test the gearing theory over the weekend with some short efforts around 500 W in my lowest gear in ERG mode. I’ll report back with the results.

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I’ll be interested in the low gear testing. I haven’t seen any max power vs flywheel speed graphs from trainer companies, they usually give a big number at a high flywheel speed. If I’m reading the numbers right, you were doing 450 watts at 80ish RPM in a 34/26 gear. I don’t think it’s crazy that you could be hitting the max power for that flywheel speed.

My theory for your first test is that you had some kind of interference that dropped the connection to the trainer, so that it wasn’t getting the message to increase the power after minute 18. Are you using BT or ANT for the Kickr connection?

I have had similar experiences (not in a ramp test) in my basement when someone turns on the microwave in the kitchen above me…

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A bit of a different issue here. I bought my StagesSB20 & a TrainerRoad subscription recently and got started on a training plan.
I have found that the training sessions that do not involve short-duration intervals work pretty ok (eg; Glassy -3) in terms of how the SB20 ramps-up the resistance to meet the target wattage.

However I did Grassy Ridge-3 last night and found it really frustrating as when trying to meet the power target for the 30 sec intervals my cadence shot way up (over 130 in some cases) and I simply didn’t have enough resistance to push against in order to meet or exceed the target power.

(I’m a mountainbiker not a roadie so spinning high cadence is not something I ever do - I like to push harder gears than spin fast circles.)

So for the next set of intervals I tried applying the brake in order to increase resistance and thus increase power at lower cadence.
This was better because I was able to meet (mostly exceed) the power target. It was tough however to keep the brake applied to a consistent degree to avoid power spikes - but I’d prefer to overachieve than underachieve otherwise I’m kinda wasting my time I think

I have performed various test on my SB20 & added new power meter batteries and it has the latest firmware etc… so I think the bike is ok, but the interaction with TrainerRoad is not functioning as I expect.
It would be good if I could seta max cadence value so that I wouldn’t be forced to spin crazy cadence in order to try meet the target wattage.

Has anyone else with an SB20 seen a similar issue on short-duration intervals or had to resort to using the brake to achieve their target power goals for intervals?
thanks!
Fergal

The Forum likely isn’t the best place to ‘get to the bottom of’ an issue that may be TR software related.
It can be super device/version specific, support knows best and is the quickest to provide up-to-date info (and in this instance, the action items to help). :sunglasses:

From the ‘Welcome to the TrainerRoad Forum’ Page:
Have a question about the app, your training plan, or device? Reach out to support@trainerroad.com instead of posting here. Our support team has the best visibility and insight into your devices, workouts and adaptations, and will help get you the most efficient and effective answer to your question.

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Cheers, I’ll raise a ticket with support to see what possible options there are

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Strange distinction. I’m a mountain biker too and on the climbs and hard accelerations I like a high cadence. Maybe it depends on the individual, or what you class as high cadence.

I switched to using Resistance mode (instead of ERG) and find it much better now that I can use my gears to get to the correct resistance very quickly and fully complete those short intervals.