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Drag Factor changed between warmup/workout

Posted: October 28th, 2023, 8:53 am
by allimprov
Hi,

Today I did a 16 minutes warmup followed by a 30 minutes workout. I haven't changed the drag factor for several days (I kept it at 118), and neither did I change any settings between the warmup and the workout.

However, for some reason, the drag factor was recorded as 118 during the warmup but 146 during the workout, and I have no idea why?

The warmup was quite slow and steady, while the workout was a 1' max effort followed by 2' slow and steady rest, 10 times.

How could this happen and can I trust the drag factor recorded in the workout? Could it be because I started the workout right in the max effort zone and push/pulled as hard as I could? (hence, it could have recorded the very first stroke's high drag factor because the flywheel was still, and kept it in memory for the rest of the workout?)

Thanks

Re: Drag Factor changed between warmup/workout

Posted: October 29th, 2023, 9:00 am
by Elizabeth
Assuming you are talking about the RowErg, the PM5 recalculates the drag factor on every stroke. I'm pretty sure that the displayed drag factor in the logbook shows the average drag factor for the row. I found a session where I started at DF 110 and then increased it to DF 135 for the end (I was warming up for a sprint), and my logbook shows DF 125.

It shouldn't change based on how hard or easy you are pulling.

Variations of 1-2 are super common, I will frequently see 111-110-112 as I row. If you are outside, a big gust of wind can change it even more. Moving the erg so that there's more or less air movement also seems to make a difference - especially if the fan cage is moved really close to a wall or something. But the kind of jump that you're talking about is so much that I wonder if there was some sort of bug in the calculation.

Sorry I'm not of more help.

Re: Drag Factor changed between warmup/workout

Posted: October 29th, 2023, 11:15 am
by Joebasscat
See my post from 10/22 “ErgData and Drag Factor.”

C2’s response was they could not identify at this time why that was happening. Your issue seems similar to my experience.

Re: Drag Factor changed between warmup/workout

Posted: October 29th, 2023, 11:49 am
by Dangerscouse
That does seem very strange. Did it feel different?

Re: Drag Factor changed between warmup/workout

Posted: October 29th, 2023, 12:05 pm
by Sakly
What device do you use? IOS or Android?

Re: Drag Factor changed between warmup/workout

Posted: November 1st, 2023, 10:39 am
by allimprov
Thank you everyone for your replies.

@dangerscouse: it didn't feel different at all, which is the interesting part.

@sakly I use ErgData on Android and always used the same phone/C2.

@joebasscat Checked your post and indeed, it looks quite similar.

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Yesterday I tried to replicate that in 2 steps (1: row lightly to measure the DF, stop, and then row as hard as I can for a few strokes and measure the DF again) but the DF stayed the same.

Maybe is it some kind of bug. It would be nice if we could manually edit the DF in the Logbook to correct, although it would not fix the root issue.

Re: Drag Factor changed between warmup/workout

Posted: November 1st, 2023, 6:43 pm
by Joebasscat
My first occurrence was on 9/28 and has done so on SS rows since. Prior to that, all good. All over 60”. I did a 30r20 on Saturday and all reported correctly. I increased my power on my SS on Tuesday and the error was present. I remain stumped.