Variance between PM2 & PM3

[kannankeril]

My brother & I have a Concept Model B with PM2 & D with PM4 respectively.

We got some confusing data following 25 minute rowing sessions (see below). My brother rows between 35-40 strokes/min while I row at a more sedate 21 strokes/minute. However at the end of about 25 minutes, I have the slightly greater distance, watts and calories consumed. His flywheel is set at 6 while mine is at 4.

Concept II Model B with PM2
26.5 minutes
5000 mtrs
35/40 avg SPM throughout
85-95 watts
260 cals

Concept II Model D with PM4
25 mins
5301 meters
21 strokes/min
151 watts
300 cal

Any suggestions on what we need to do to resolve the discrepancy between our two machines. We live at geographically distant locations and it is not possibly to match the two systems side-by-side.

[Citroen]

One of you is stronger, pulling more metres per stroke.

85-90W @ 35-40SPM tends to point to a technique problem.

[kannankeril]

How likely is it that one of the PM monitors is calibrated incorrectly?

[TabbRows]

How likely is it that one of the PM monitors is calibrated incorrectly?

Not likely. Dougie is correct.

Your brother is only pulling a 2:39 pace and getting ~5 meters a stroke for his ~1000 strokes; you're pulling a slightly faster 2:21 pace, ~525 strokes and getting ~ 10 meters a stroke. Poor technique is probably at play here.

But are you sure your brother has a "B"? With a wire cage, not an enclosed cage? "B"'s don't have # settings for the flywheel; they have adjustable vent openings on the damper and the drag factor depends partially on which chian cog you are in as well as how far open the vents are (among various other sundry things).