Strange spm spikes on easy pull

[Citroen]

Is that an old model C? I see SPM spikes on PM3s on the old model Cs in the gym all the time. One suggested solution is to take the flywheel sensor off the machine and give it a thorough clean. The other solution is to replace the sensor with a new one.

I've merged the threads, please don't spam the forum with multiple threads on the same topic.

[kris-o]

1. This is new model D/PM5 - bought in late 2015 ... if you check the posts, you will see that everyone got that already
2. The nature of the issues is different so i have decided to open 2 threads, to keep this forum clear and consistent:
- first issue - easy to reproduce (happening ALWAYS) SPM spikes on EASY pull - solved by replacing battery and upgrading to beta software
- second issue - occasional SPM spikes in NORMAL pull - hard to reproduce, happening once every 5-10 minutes - NOT YET solved, probably caused by inconsistent pull, coming from poor technique (will monitor and report about that later on, as i improve)

This forum has 1 or 2 threads a week. I have found posts touching "my" problem ... but without any follow-up/explanation - i have decided to provide this follow up, and give some extra info. This way, people visiting this forum, looking for answers, can save time or have at least some starting point for their investigation.

Would be nice if you granted me some of your precious time and, at least, read two threads, before giving names...
Have a nice evening/day

[lcantey]

1. This is new model D/PM5 - bought in late 2015 ...

FWIW: The ones I've seen it on are late 2014 and one purchased direct from Concept2 a couple of weeks ago.

[Dwalin]

Can confirm the issue on a DPM5 purchased 1 week ago.

Due to disability I usually keep a pace between 4:30 and 5:30 / 500m, this made the spm spike very frequently into the 90s and 250s (logged by FR610).

After upgrading to the beta firmware from February the problem has been reduced significantly.

Thanks for the tip.

[kris-o]

Yes, after some additional testing i suspect that inconsistent pull technique is causing the flywheel's accelerometer to count one stroke many times.
This phenomenon was visible in my rowing, when i was going slow - sloppy pull was not fluid and probably has been counted as many separate strokes (3-4).
This was causing SPM jumps to 60-90s.

Last 3 days i was going bit faster with lower SPM, doing stronger, steady pulls. The problem disappeared (max SPM - 24, instead of 109 or 106).

So to sum things up - i have encountered 2 issues with SPM:
1. easy to reproduce SPM spikes on easy pull - fixed by upgrading PM5 to the latest beta or replacing batteries (i suspect firmware)
2. random SPM spikes during "normal" rowing with easy pace - caused by sloppy pull technique and uneven pulls (one stroke counted 3-4 times because of the uneven character of my "pulling force" fooling flywheel's accelerometer)

Hope that helps

[MikeCooper]

Thanks for the posts, guys. I'm a brand new rower - got my Model D a couple of weeks ago - and had been noticing occasional spikes in my own SPM, even though my pace has been fairly steady in the 23-25spm range. (So I was surprised to see it jump momentarily to 84 or similar!)

I think the posters who've mentioned the idea of electrical interference may be onto something. I'll monitor more closely, but my spikes may even be happening more on days where the AC unit is running in my gym room (the heat pump is just the other side of the wall) rather than when I'm just running the fan section. There's also a freezer in the next room. It's quite possible that either of these cycling on and off is generating RF noise that the PM5 or sensors might be susceptible to.

[Citroen]

Open the cage and clean the hall effect sensor. It's caused by missing a reading from one of the magnets on the flywheel.

[MikeCooper]

OK - but I'm a bit puzzled. Should that be necessary on a brand new machine?

And if it is, how do I do that? (I tried Googling "concept2 model d clean sensor" but find links to articles on this forum saying to do it, but not how to do it…)

Thanks!

[c2jonw]

The Model D has a much more robust sensor/magnet system than the one Citroen refers to, which was used on Models B and C. Cleaning should not be the issue, especially on a relatively new machine. Very possible it's your technique, as noted by kris-o in his March 24th post. This phenomenon can be viewed on the Force Curve screen of the PM. The curve should be smooth and shaped like a gumdrop. Significant breaks in the power application during the drive will momentarily cease acceleration of the flywheel, which the monitor will interpret as the end of the stroke. It's not hard to get a double or triple count in one stroke.
Read more about using the Force Curve here: http://www.concept2.com/indoor-rowers/t ... orce-curve

C2JonW

[chrisl]

I noticed similar spm anomalies on the ErgData graph from my HM yesterday. There were occasions when I stopped rowing for a moment to adjust my seat or to use a towel and take some water. At those points the pace takes a momentary dip and you can see the spm readings tend to spike at those same points. This implies the spikes are simply caused by the logic, which works out the rate based on the rate so far, detecting a rise from 0 to whatever it actually is, and computing the rate of change as a huge spike. Ideally the logic should be improved in future to throw away such spikes as outliers.

Regards,
Chris