BikeErg Monitor Calibration

[Slidewinder]

I don't own a BikeErg. I am puzzled as to how the BikeErg monitor self-calibrates. On the RowErg and the SkiErg there is a drive and a recovery during use. The monitor on these units re-calibrates DF on the recovery by measuring the deceleration of the flywheel, but on the BikeErg there is no recovery period. The power delivery by the user is continuous, so it would seem that there is no opportunity for the monitor to recalibrate. How then is the PM self-calibration achieved?

[gvcormac]

There's an angle sensor on the damper lever. At the outset, and from time to time, you need to calibrate the PM5 by spinning it up and letting it coast down at various damper settings.

Before any verified event you need to do a quick calibration verification, spinning up and coasting down at a single damper setting.

You can cheat big time by blocking the fan input, but if you don't do that the calibration seems pretty good.

As you note, the RowErg and SkiErg don't need a damper sensor. In effect, they recalibrate after every stroke.

[Slidewinder]

There's an angle sensor on the damper lever.

So the angle sensor communicates with the PM via an additional cable?

[gvcormac]

There's an angle sensor on the damper lever.

So the angle sensor communicates with the PM via an additional cable?

There's a cable to the angle sensor. It is hard to tell from visual, but I think it splices into the main cable at the flywheel rotation sensor. There is only one physical cable coming from the PM5 down the handlebar stalk, and there is a cable from the base of the stalk to the angle sensor. This is a bit annoying when your remove the fan cage because it tugs on the cable.

It is kind of hard to determine the exact routing from an external inspection, and the schematics don't illuminate much: https://www.concept2.com/service/bikeer ... schematics

[Slidewinder]

There's an angle sensor on the damper lever.

So the angle sensor communicates with the PM via an additional cable?

There's a cable to the angle sensor. It is hard to tell from visual, but I think it splices into the main cable at the flywheel rotation sensor.

Interesting. The monitor cable on the BikeErg schematic has Part #2407, which is a part not listed on the RowErg schematic, so you seem correct that the angle sensor cable is spliced into the main PM cable.

It interests me because I suggested in a past thread with respect to the RowErg that a force sensor at the connection point between the chain and the shock cord, or between the shock cord and the frame, could be used to monitor the force required by the user to stretch the cord throughout the entire stroke, from drive to recovery, and through the appropriate programming of the PM, calculate the power specific to this and adjust the user pace accordingly. This would end any debate about whether degradation of shock cord strength with time and usage affects equivalence between machines -because the force profile of the shock cord would always be included in the PM calculations and integrated in the display. As you know, as built, the PM on the RowErg does not measure the power to stretch the elastic cord, only the power to drive the flywheel, so unless the force profile of the elastic cord remains a constant throughout the life of the machine, the equivalence between machines is legitimately questioned. A force sensor at the elastic cord and appropriate PM programming would put that question to rest.

[JaapvanE]

A force sensor at the elastic cord and appropriate PM programming would put that question to rest.

You realize this is a highly moving part right? From a reliabilty point of view, you don't want any sensor there. There is a formal test procedure in place to test the shock cord every 250 hours of use. Apperantly that is sufficient.

And apart from that, there are too many moving parts which combined have a much greater effect when dried out. So are you going to measure them as well?

When you consider this problematic and want to get rid of these measurement issues (?) with the PM5, buy a WaterRower with the SmartRow add-on, then these are all solved.

[gvcormac]

How does SmartRow measure force? The blurb is unclear.

It looks like it replaces one of the belt pulleys. I suppose it could measure lateral force on the axle of the pulley to gauge force on the belt. But that's speculation on my part.

[JaapvanE]

How does SmartRow measure force? The blurb is unclear.

It looks like it replaces one of the belt pulleys. I suppose it could measure lateral force on the axle of the pulley to gauge force on the belt. But that's speculation on my part.

It does replace a pulley indeed, it replaces the top pulley (the one where the belt makes first contact with the rower). Although schematics are not to be found anywhere, I suspect they indeed measure the force on the axle or the outer rim, and the rotation. They say something of that liking here: https://smartrow.fit/images/smartrow-wo ... xcerpt.pdf As this article suggests it is an excerpt of a Journal article, I tried to find the entire thing, but it seems it isn't published (Google Scholar has no record of it).

Lotte Lintmeijer has done her PhD on biomechanics of rowing and the effects on feedback, but her PhD thesis is only concerned with OTW rowing, so no data there. Knoek van Soest has quite long record in this field, but I couldn't find any papers regarding this validation in his publications (see https://research.vu.nl/en/persons/knoek ... lications/ ). I am a lector at the VU, with good connections to the electronics lab , so next year I'll ask around.

[gvcormac]

Lotte Lintmeijer has done her PhD on biomechanics of rowing and the effects on feedback, but her PhD thesis is only concerned with OTW rowing, so no data there. Knoek van Soest has quite long record in this field, but I couldn't find any papers regarding this validation in his publications (see https://research.vu.nl/en/persons/knoek ... lications/ ). I am a lector at the VU, with good connections to the electronics lab , so next year I'll ask around.

I couldn't find the article either. Or a patent.

[Slidewinder]

A force sensor at the elastic cord and appropriate PM programming would put that question to rest.

You realize this is a highly moving part right? From a reliabilty point of view, you don't want any sensor there.

And apart from that, there are too many moving parts which combined have a much greater effect when dried out. So are you going to measure them as well?

Both ends of the shock cord are terminated separately at fixed points. The chain pulls from the middle of the shock cord. Either of the fixed points would be suitable for the described force sensor installation.

"There are too many moving parts which combined have a much greater effect..." You are referring to the various pulleys, sprockets, and rollers? These all have sealed bearings. The resistance of those sealed bearing remains effectively constant throughout their life and therefore do not affect equivalence between machines. The resistance profile of the shock cord does not remain constant throughout its life and therefore, arguably, does affect equivalence between machines. A force sensor installation as described would correct this problem.

[JaapvanE]

These all have sealed bearings. The resistance of those sealed bearing remains effectively constant throughout their life and therefore do not affect equivalence between machines. The resistance profile of the shock cord does not remain constant throughout its life and therefore, arguably, does affect equivalence between machines. A force sensor installation as described would correct this problem.

You have too much trust in the (lack of) production tolerances....

[Slidewinder]

These all have sealed bearings. The resistance of those sealed bearing remains effectively constant throughout their life and therefore do not affect equivalence between machines. The resistance profile of the shock cord does not remain constant throughout its life and therefore, arguably, does affect equivalence between machines. A force sensor installation as described would correct this problem.

You have too much trust in the (lack of) production tolerances....

I trust that C2 has sourced quality sealed bearings for the RowErg - bearings that maintain a near constant resistance over their life-span. You, as one of this Forum's leading C2 cheerleaders, must surely also have that trust.

[JaapvanE]

I trust that C2 has sourced quality sealed bearings for the RowErg - bearings that maintain a near constant resistance over their life-span. You, as one of this Forum's leading C2 cheerleaders, must surely also have that trust.

I am not a cheerleader. If you want to conduct an intelligent conversation with anyone, you should refrain from this type of name-calling.

With this, I conclude my contribution to this thread.

[Slidewinder]

I trust that C2 has sourced quality sealed bearings for the RowErg - bearings that maintain a near constant resistance over their life-span. You, as one of this Forum's leading C2 cheerleaders, must surely also have that trust.

I am not a cheerleader. If you want to conduct an intelligent conversation with anyone, you should refrain from this type of name-calling.

With this, I conclude my contribution to this thread.

As an electronics expert you should be eager to discuss the merits of my described force sensor installation at the shock cord to frame connection point on the RowErg - as a means for the PM to compensate for changes in the shock cord force profile over time, thereby ensuring equivalence between machines. Instead you pretend to be insulted and run for the exit. You declare, "I am not a (C2) cheerleader." - This from the guy who, in a recent thread, argued that the bronze bushing at the handle swivel connector was prone to breakage because C2 deliberately engineered it to be a type of fuse to protect other components of the RowErg drivetrain. Thanks JaapvanE for my morning chuckle with that post.

[JaapvanE]

As an electronics expert you should be eager to discuss the merits of my described force sensor installation at the shock cord to frame connection point on the RowErg - as a means for the PM to compensate for changes in the shock cord force profile over time, thereby ensuring equivalence between machines. Instead you pretend to be insulted and run for the exit.

No, I am insulted. This kind of namecalling for anyone who disagrees with you is just childish.

You declare, "I am not a (C2) cheerleader." - This from the guy who, in a recent thread, argued that the bronze bushing at the handle swivel connector was prone to breakage because C2 deliberately engineered it to be a type of fuse to protect other components of the RowErg drivetrain. Thanks JaapvanE for my morning chuckle with that post.

The fact that you don't recognize a Sacrificial component when you see one is a clear limitation in your (lack of) training, not in mine.