Strange spm spikes on easy pull

[kris-o]

Hello,

I have recently noticed that my PM5 is acting weird when i do really easy pulls - spm jumps to 60 or 80 and is all over the place.
In order to have good reading i have to give a strong pull.

Im not sure whether this is a problem or not, i have noticed it only now because i am recovering from some injuries and have to maintain low HR (that forces me to do some easy meters during my workout to let the HR settle).

How is that sensor supposed to work? Is it bike-like sensor with magnet or some g-force based solution?

[Carl Watts]

Is it configured for the right model of Concept 2 rower ?

The model C had 3 magnets in the flywheel but the Model D onward has a multi pole magnet and is totally different.

Have a look in the product ID screen for the rower its configured for.

[lcantey]

I have recently noticed that my PM5 is acting weird when i do really easy pulls - spm jumps to 60 or 80 and is all over the place.
In order to have good reading i have to give a strong pull.

Im not sure whether this is a problem or not, i have noticed it only now because i am recovering from some injuries and have to maintain low HR (that forces me to do some easy meters during my workout to let the HR settle).

I have noticed it occasionally, but I see it much more often for my daughter and I just saw it today with my friend who just got his rower this weekend. I never took the time to try and replicate it but I've now seen it on more than one model D PM5 rower.

[jamesg]

I see it quite often. C/PM3. Not a problem as it has no visible effect on averages.

Given the way the sensor/computer works, it's probably missing or extra impulses due to spikes in home power supplies, dodgy contacts or screening, or similar.

When the spikes appear, the force curve also shows scattered or missing data points.

When I last changed the sensor and its cable (PM3), these spikes decreased in number. If I connect the PM to a laptop, they increase; if the laptop is connected to a power supply, I get still more.

So the basic problem could be that the sensor gives low level signal; and any phenomenon that gives a power spike, such as lightning, large motors switching on/off, will cause an odd reading if the SW can't filter it out. Just guessing. Maybe an industrial encoder would give a stronger signal, with Internet of Things.

One day I'll try switching off the entire home electric system, see if it makes any diff.

[kris-o]

I am not sure whether you are referring to the same thing. In my case, i can easily reproduce these spikes - they are not rare or random.
Simply, when i pull really easy, spm jumps to 60,80,90 - randomly.

Could anyone with D/PM5 try to do the same and report about results? Just sit and do very slow pulls - only enough to move the wheel, without "g-force" pull (not accelerating the wheel).
I have also noticed that my batteries went from 80% to 12% recently - not sure if i forgot to turn wireless OFF, and also not sure whether these 2 are related.
Rower should be able to power itself during workout, right? (i am not using USB, i AM using HR belt and BT connection to phone)

[Carl Watts]

Certain hardware versions of the older model PM3 have problems on Firmware V108 on a Model C only.

Nothing to do with interference, you need to go back to V105 if you want the problem to go away.

The fault is just single strokes now and again showing a much faster pace, but not rating that I can remember.

There should be no problems with the PM5 on a model D. Check the configuration and also update to the latest firmware as no one else has reported the same fault.

[kris-o]

I have bought this rower in late december 2015 and upgraded to the newest firmware back then. I think that there was no new release since that day...?

[jamesg]

Simply, when i pull really easy, spm jumps to 60,80,90 - randomly.

Rating is calculated from the time between successive max impulse rates, so PM has to see at least 2 strokes. The first stroke alone cannot provide data for stroke rate. We see 0 if starting dead, and any number if starting live, i.e. with the already PM running, but after a long pause.

You need to pull at least 12-15 strokes per minute.

[Bob S.]

You need to pull at least 12-15 strokes per minute.

Actually 10 will work, if you hold it steady. At 9, the spm reported on the monitor will jump all over the place.

[kris-o]

10 would mean one stroke per 6 seconds. I am pretty sure that i am putting bit more than that and PM5 is showing 90 or 60. This is done mid-workout so there is no talk about single strokes. Somethings fishy ...
Also, i have noticed that it won't turn on without the batteries. Just updated with the beta 20.010 ( i assumed that it was more recent than 720.005 - right?).
I didn't have a chance to give a good try without batteries - just did some pulls with the rower disassembled (very easy) and PM5 was at least blinking - gives hope

[George Wright]

RE: Mod D, PM5, firmware 20. If I row very, very, very slowly then I can see that the SPM reads quite high. However, when I begin rowing even at the low end of normal then the PM5 reads accurately after about two strokes. This might indicate something in the design of the sensor rather than a real problem. Personal, I consider this to be an observation, not a complaint.

[kris-o]

Yes, me too. However, i would like to add that the "problem" is almost gone after changing the batteries and updating firmware to the 20.010 beta (not sure which of these helped as i didn't test in between).

I suspect that there actually might be some issue underneath because even now i can see often spm spikes to 90. These happen while steady rowing at low spm (18-22, easy pace around 2:30)
I am not bothered by this big time but i kinda don't like it- when there is a field that is displaying some value, i would like to have this value correct. The measurement method does not change, the hardware does not change, the software does not change so why do i have sudden spikes?
I suspect that there might be some PM5 s/w issue because this thing looks to me a bit "half way there" - doesn't give a feeling of being rock solid and stable (crashes, constant problems with USB, Bluetooth etc.)

[kris-o]

I have decided to open another thread for my ongoing SPM investigation, as the nature of the current "problem" is bit different.
I have contacted Concept2 about my spm concerns and they provided me with another PM5. I have connected it to my model D and performed 30 minute test.
Result: i can still see short SPM spikes - they are visible on PM5 screen - the SPM jumps to something around 80-90 for a brief moment (just one refresh of the reading on PM5 screen).
Can you guys see it too?
I just want to know whether this situation is a symptom of some h/w issue approaching or its just "normal operation".
Its not like i cannot live with it, i love this rower

[lcantey]

I replied on the other thread but I'll also reply here. I've seen the spikes on the output from two different PM5s. They are noticeable in the stroke graph when you use the newer ErgData to upload rows. I don't see them often in my rows but they are much more prevalent in my young daughter's rows and also with a friend of mine who just started rowing.

[kris-o]

Ok, I've thought that you were referring to the spm spikes on easy pull. Those are gone in my case. Now I can see only short spikes now and then.
I am also quite new to rowing - maybe my technique is inconsistent - you have mentioned 2 persons probably not experienced, right? (Not trying to offend your friend or daughter by any means )