Vo2 Max and drag factor stats

[eglin73]

Hi,

Since upgrading to 0.96 I'm getting some unexpected stats at the end of my rows:

This is from the rowing.tcx file which is where I used to look to get a V02 stat:

Indoor Rowing, Drag factor: 1837.1 10-6 Nms2, estimated VO2Max: 0.0 mL/(kg*min)

and this is from the Strava upload for the same row:

Drag factor: 528.5 10-6 Nms2, estimated VO2Max: 53.4 mL/(kg*min)

I expect my drag factor to be around 530-560, so the rowing.tcx file's drag factor is much higher than I would expect, and it does not have a vo2 figure.

Config is:

createRawDataFiles: false,
gpioMinimumPulseLength: 100,
gpioPollingInterval: 5,
gpioTriggeredFlank: 'Down',
userSettings: {
weight: 80,
sex: 'male',
highlyTrained: true,
strava: {
allowUpload: true,
autoUpload: false,
clientId: "105719",
clientSecret: "",
refreshToken: "",
},
},

rowerSettings: {
  numOfImpulsesPerRevolution: 3,
  minimumTimeBetweenImpulses: 0.01,
  maximumTimeBetweenImpulses: 0.2,
  dragFactor: 550,
  flywheelInertia: 0.138,
  flanklength:8,
  magicConstant: 2.80,
  numOfPhasesForAveragingScreenData: 4,
  peripheralUpdateInterval: 500,
  autoAdjustDragFactor: true,
  autoAdjustRecoverySlope: true,

Thanks Ian

[JaapvanEkris]

This is strange, as it essentially is the same function providing the data. Might be a timing issue here. We did move away from using tcx files for Strava, as the FIT-fie contains more data, and is more compact. Could you set it to write to file, and see what the timestamps and content say (a site like fitfileviewer.com is helpfull here).

[eglin73]

Thanks Jaap. It was quite hard to try and make sense of the time stamps as I had not set the timezone correctly. I've done that now and will take a look once I have a new row that is over 2000m

Thanks
Ian

[eglin73]

Hi Jaap,

Having sorted out the time zones on the raspberry pi, I have managed to get a row that shows the issue and the supporting logs and files. Hopefully it helps to understand why it is.

This is what [Strava]([2025-12-16_01-10-23_rowing.fit - FIT File Viewer.pdf

Drag factor: 540.0 10-6 Nms2, estimated VO2Max: 52.6 mL/(kg*min)

But the tcx (attached) shows no Vo2.

I have attached the .tcx, a pdf print of the fitfileviewer, and a copy of the log.

Thanks again
Ian

Log file.txt
2025-12-16_01-10-23_rowing.fit - FIT File Viewer.pdf
tcx.txt

[JaapvanEkris]

Just a heads up from my side. I haven't forgotten this issue. It just takes a bot more time to find the underlying cause. I think I found the cause of the VO2Max issue, and I put in a fix in the 0.9.7 branch (see https://github.com/JaapvanEkris/openrowingmonitor/tree/0.9.7-(under-construction) ).

The dragfactor is weird, as the data is based on the same report, and in my own setup it works. So I have to dig a bit deeper there.

[eglin73]

No problem, and thanks for the update Jaap. I'm away at the moment but will try the VO2 fix when I get back. HNY to you, thanks for your continued work on ORM. Regards Uan

…

On Thu, 1 Jan 2026, 01:34 Jaap van Ekris, ***@***.***> wrote: Just a heads up from my side. I haven't forgotten this issue. It just takes a bot more time to find the underlying cause. I think I found the cause of the VO2Max issue, and I put in a fix in the 0.9.7 branch (see https://github.com/JaapvanEkris/openrowingmonitor/tree/0.9.7-(under-construction) ). The dragfactor is weird, as the data is based on the same report, and in my own setup it works. So I have to dig a bit deeper there. — Reply to this email directly, view it on GitHub <#156 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/A67ZYID6QSCKMFV4KXNSN3D4EPNGJAVCNFSM6AAAAACOGPP5FOVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTKMZYGE2TSNQ> . You are receiving this because you authored the thread.Message ID: <JaapvanEkris/openrowingmonitor/repo-discussions/156/comments/15381596@ github.com>