Ergdata readings

[Maskerg]

I have recently retrofitted my Model C with a new PM5. After a couple of rows and looking at my info on ergdata, there seem to be some strange readings.
First I am getting spikes in spm, rowing in the 22-24 range but seeing spikes of over 100spm. Along with this it looks like there are drops/spikes in the force curve during the row. Is it possible this odd reading is based on poor form?

Second, during the row I am seeing a drag factor around 130-140 on the PM/in Ergdata but the final log is showing anywhere from 190-230.

I opened up the flywheel and all three magnets are in place and it is very clean. I am running the newest firmware on the PM5 (255).

Any thoughts or feedback would be greatly appreciated!

[jamesg]

Had those faults with a PM3 on a C, disappeared after switching to PM5. On a C, the PM must be explicitly for that model. There'll be a large C label on its back.

[Tony Cook]

I have recently retrofitted my Model C with a new PM5. After a couple of rows and looking at my info on ergdata, there seem to be some strange readings.
First I am getting spikes in spm, rowing in the 22-24 range but seeing spikes of over 100spm. Along with this it looks like there are drops/spikes in the force curve during the row. Is it possible this odd reading is based on poor form?

Second, during the row I am seeing a drag factor around 130-140 on the PM/in Ergdata but the final log is showing anywhere from 190-230.

I opened up the flywheel and all three magnets are in place and it is very clean. I am running the newest firmware on the PM5 (255).

Any thoughts or feedback would be greatly appreciated!

Not insulting your intelligence but thinking of the obvious thing first - is your PM5 configured for your particular model of erg?

[Maskerg]

I have recently retrofitted my Model C with a new PM5. After a couple of rows and looking at my info on ergdata, there seem to be some strange readings.
First I am getting spikes in spm, rowing in the 22-24 range but seeing spikes of over 100spm. Along with this it looks like there are drops/spikes in the force curve during the row. Is it possible this odd reading is based on poor form?

Second, during the row I am seeing a drag factor around 130-140 on the PM/in Ergdata but the final log is showing anywhere from 190-230.

I opened up the flywheel and all three magnets are in place and it is very clean. I am running the newest firmware on the PM5 (255).

Any thoughts or feedback would be greatly appreciated!

Not insulting your intelligence but thinking of the obvious thing first - is your PM5 configured for your particular model of erg?

Thanks for the reply. Yes, I have set the PM to Model C in the utilities menu.

[Carl Watts]

Used to see that problem with RowPro years ago and using the PM3. For a 30 minute row it would spike 2 or 3 times during the row for no reason.

Turned out that is only affected certain hardware versions of the PM3 for some reason.

As long as the PM5 is set to the right model of Concept 2 rower, there is not much you can do about it.

It would pay to check that the pickup sensor measures about 105 Ohms with a multimeter, the connector is clean and free from corrosion and you still get 105 Ohms when you wiggle the cable to the connector.

Check the three magnets embedded in the flywheel, they should appear shinny and be able to hold the weight of a paper clip.

Other than that its possible a future firmware release sorts the problem.

[Maskerg]

Used to see that problem with RowPro years ago and using the PM3. For a 30 minute row it would spike 2 or 3 times during the row for no reason.

Turned out that is only affected certain hardware versions of the PM3 for some reason.

As long as the PM5 is set to the right model of Concept 2 rower, there is not much you can do about it.

It would pay to check that the pickup sensor measures about 105 Ohms with a multimeter, the connector is clean and free from corrosion and you still get 105 Ohms when you wiggle the cable to the connector.

Check the three magnets embedded in the flywheel, they should appear shinny and be able to hold the weight of a paper clip.

Other than that its possible a future firmware release sorts the problem.

The magnets all hold a bobby pin no problem and the pickup was measuring steady 106 ohms even when wiggling the cable.

I recently did a slower pace longer row, the spm spikes are still there but the DF was accurate to what the PM showed throughout, reading was 130. Compare this with a higher intensity interval the day prior, same damper setting, where the final log has the DF at 188. My understanding is that DF is more or less a constant and doesn't change based on the intensity of the row. Maybe I am wrong?

I guess I wait for firmware update at this point, unless there are any other troubleshooting options. Thanks for the suggestion

[Carl Watts]

The DF can or should only change very slightly depending on the type of row, intensity and rating etc.

All you can really do is wait for firmware updates and newer versions of ErgData. In all honesty it will probably not get fixed.

The Model D pickup is totally different to the Model C and was vastly improved, it went from 3 magnets to a 12 magnet system so its getting vastly more pulses per revolution to work with in the math.

[JaapvanE]

The Model D pickup is totally different to the Model C and was vastly improved, it went from 3 magnets to a 12 magnet system so its getting vastly more pulses per revolution to work with in the math.

Eeeeeh, no. Having worked with the raw signals from both machines, and having built three physics engines interpreting them, and spending over a year validating the latest engine (over 1800K), I can confidentelly tell you are actually wrong. First of all, it is a 12 pole magnet, providing a continous sinoid-like signal with 6 (NOT 12!!!!) peaks. The RowErg and newer D's with the new magnet configuration actually provide a bit typical signal, as there seems to be a sinoid modulated on top of it.

I don't know HOW C2 interprets it, they could go fully analog, use some Fourier transformation, or they do some other mathematical/digital magic. But, a more finegrained measurement certainly doesn't automatically translate into better measurements. First of all, as the timing between magnet pulses is halved (a C's time between pulses varies between 30ms to 9ms where a D varies between 15ms to 4ms), the signal to noise ratio by definition increases significantly. And as the numbers become smaller, so beome the number of significant number of digits (i.e. you lose a digit due to times becoming smaller).

And doubling the number of datapoints often doesn't increase accuracy that much. For example: drag calculation with 6 datapoints per rotation gives you around 200 datapoints to work with, resulting in a 98% fit with the data. On a C, I get 3 datapoints per rotation, which results in 100 datpoints to work with, and a similar 98% fit with the data. Most calculations act similar: distance and velocity are based on the angular distance travelled, combined with this drag. Measuring it more accurately actually doesn't help for linear distance traveled, as it typically is just counting pulses and applying the formula and calculated across the stroke. Powercurve calculation isn't more accurate anyway, as the calculated values seem to get bucketed to 32 datapoints per drive anyway. Only benefit is to have more accurate measurement of drive time, drive length etc., which are interesting metrics but not life changing.

[Carl Watts]

12 magnets in that ring, they alternate poles. 6 N-S and 6 S-N they alternate so that's 12 magnets. Didn't say anything about the actual number of pulses.

Sorry its a better system full stop and the later versions of the pickups can supply enough current to run the monitor.

I'm not going to bother to go into the math or the electronics, nobody is really interested, however a few were suddenly interested when I managed to produce a fake verified time and that's only more practical to do on the Model C. The aim was to test how reliable the results would be going to a verified only meters Challenge and I can say after testing very reliable and getting more reliable by the year, unfortunately Concept 2 didn't get it and still do not have a verified meters only challenge.

The Model D is just better, never had a Tach pickup fail in the electronics in over 10 years, the cable eventually failing at the right angle connecter is a different story. If you take the rowing seriously you will have a Model D by now, everything else is now 20 years old.

[jamesg]

I guess I wait for firmware update at this point, unless there are any other troubleshooting options.

With my PM3 I suspected spikes be due to mains interference, since the flywheel signal frequency can be in the range 50-60Hz. Got much worse when connected to a powered laptop.

The PM5 must have a C label on it.

[Maskerg]

I guess I wait for firmware update at this point, unless there are any other troubleshooting options.

With my PM3 I suspected spikes be due to mains interference, since the flywheel signal frequency can be in the range 50-60Hz. Got much worse when connected to a powered laptop.

The PM5 must have a C label on it.

The PM does not have a C marking on it. But it is the retrofit kit for Model C and there is the ability to set the PM for Model C in the Utilities menu, so I don't think that is the issue.

[Cyclist2]

The Model D is just better, never had a Tach pickup fail in the electronics in over 10 years, the cable eventually failing at the right angle connecter is a different story. If you take the rowing seriously you will have a Model D by now, everything else is now 20 years old.

Hey Carl, had to chime in here. No doubt the Model D is "better" (although some of the plastic parts could have stayed metal) but I have to disagree that if you're serious about rowing, you have to have a model D. I'd amend that to say, if you're serious about electronics, online connectivity, automatic workout recording and detailed workout stats, then you might need a model D/PM5.

I'm still rowing my model C with PM3 and occasionally my model B with PM2, and I consider myself a pretty serious rower. Sure, I have to enter results manually (and verification codes for ranked pieces - thread crossover there). But I'll bet my rowing workouts are just as productive or intense as anyone with all the latest electronics/internet gear. And based on the number of forum threads with problems people have with all that high-tech stuff, I probably spend less time with pen and paper than they do trying to sort out all the various glitches.

Don't want to start a flame war here, just saying that some of us rowers are just fine with older technology.

[Carl Watts]

Don't want to start a flame war here, just saying that some of us rowers are just fine with older technology.

Once you move to the PM5 you just never look back.

Unless you have a PM4, by far and away the biggest improvement in the PM5 is the ANT+ heartrate so if you are not even watching your HR, then really not what I would call a serious rower.

Then there is ErgData on the phone, great addition but to be honest I just stayed with the old version. I also look forward to the day that the likes of ErgData is the only way you can upload results to the C2 Log.

The PM5 on the Model D is just better all round, several engineering improvements, its just smoother. Sure you can update the Model C with a "Quiet Kit" and its pretty much the same as the D, but then you are really only agreeing the D is better.

Yes I still have my Model C I purchased in 2000 and also have a Model D, the Model C now sits in the corner of the garage on its nose and is only used to test PM2 monitors really, pretty expensive test jig.