Spiking stroke rate even after PM5 replacement

[Mwoodburn]

Hey everyone. Very frustrating issue I'm having. During my rows very frequently my stroke rate will suddenly spike to 80+ SPM several times in one session.

After much troubleshooting with customer service they sent me a new performance monitor. However, same issue.

I'm wondering now if it's something to do with my Bluetooth devices messing with the PM5. I use a garmin HRM Pro Plus strap, and I wear a venu 2 plus watch and I set the row activity when I row. I also connect my phone via the Ergdata app.

I suppose my next step in troubleshooting will be to not use my watch or heart rate strap, but I hope there's another explanation I like recording all the data if possible.

Just want to hear your thoughts on if anyone else has encountered this issue.

Thanks!

[Citroen]

Check all the magnets on the flywheel.
Are they there?
Are they close enough to the pickup to register?
Are they magnetic enough?

[jamesg]

Presumably the PM identifies the end of a stroke when it sees the handle slow down. This could happen when legs-trunk stop working and the arms start. Maybe the force curve can show something, as also ergdata.

I saw plenty of spikes on a C with PM3, but not when new. Maybe I was newer too. As far as I could see, average power was were not affected

[Cyclist2]

The latest PM5 firmware update cured the spikiness. Here is a thread I started when I got a new PM5 for my Model C.
The beta fix they had me download has now been incorporated into the latest update. viewtopic.php?f=10&t=207616

I still get a random spike, about one per workout, but I got that on my PM3, too. It doesn't affect the overall averages, although sometimes the instantaneous readings will change, but they level out soon enough.

Check your firmware and make sure your ErgData has the latest update, too. I have my PM5, HR belt, and earbuds playing music all connected to my iPhone via Bluetooth with no problems.

[JaapvanE]

Presumably the PM identifies the end of a stroke when it sees the handle slow down. This could happen when legs-trunk stop working and the arms start. Maybe the force curve can show something, as also ergdata.

This is indeed how a PM5 works. Although a bit inaccurate, it is solid as hell. But a small stop in a transition might cause a slowdown in the flywheel, and thus makes the PM5 think there is a recovery.

I saw plenty of spikes on a C with PM3, but not when new. Maybe I was newer too. As far as I could see, average power was were not affected

On a PM5 there are some "half strokes" sometimes recorded (you can see them when you download the excel file via C2). There are approaches to power and pace calculation that are largely unaffected by where the stroke ends, which C2 also seems to use.

[multi21]

Are you pausing for more than a few seconds during your rows? For me, any pause of that duration gets registered as a stroke rate spike. I am not sure if that is intended behavior or not.

[c2jonw]

How old is the machine and did this problem start recently? Have you looked at your force curve? I recall a fellow who had this issue and after multiple new monitors and speculation that it might have something to do with his personal electrical field (!!), it was determined that he was separating the leg and arm power delivery to the point that the flywheel was, for a moment, not accelerating during the drive. This was seen by the monitor as the end of the drive followed immediately by an acceleration and then the normal deceleration at the real end of the drive. This would all lead to erroneous stroke rate values and it was very evident once he looked at the force curve. It may also be something mechanical such as the sensor or the flywheel magnet(s). If you have access to another machine you could try swapping flywheels and sensors to see where the problem goes. Good luck!

[GreenStratMan]

I've had this and as Jon says; for me, it was down to technique.