Concept2 Forum

I quickly put together an interactive chart mapping pace, power, cal/hour and speed for Concept2 ergometers. These are the same values you see on the erg monitor. Having them all overlaid in a single chart might be useful when planning how to attack a workout.

https://ergarcade.com/articles/c2-pace-derivatives.html

Fakafetai!

A great chart ... but with one problem.

Your chart 'speed' is double actual speed.

2:00 pace is 15km/hr, your chart shows up as 30km/hr

robbiep wrote: ↑

September 3rd, 2020, 3:39 pm

A great chart ... but with one problem.

Your chart 'speed' is double actual speed.

2:00 pace is 15km/hr, your chart shows up as 30km/hr

This. Fix the distance issue in your calculation and you have a pretty helpful chart.

Thanks for picking that up. I was originally working on the BikeErg numbers so pace is off for SkiErg and rower. Fixed now.

The calorie calculation is not the same as used by the PM. At pace 1:40, the difference is almost 300 kcal/hour.

The PM uses 4 * mechanical work/hour + 300 kcal/hour. (I am not going into a discussion of whether this is better or worse. Just pointing out the difference).

Also, the unit in the diagram is cals/hour. Should be kcal/hour.

Hi Allan,

Allan Olesen wrote: ↑

September 4th, 2020, 3:26 am

The calorie calculation is not the same as used by the PM. At pace 1:40, the difference is almost 300 kcal/hour.

I recorded this video of rowing for 1:00 at 2:00, 1:50 and 1:40. The monitor shows pace, ErgData shows cal/hour. Matching paces onto the chart shows the same cal/hour value - 2:00 is 1000cal/hour, 1:50 is 1200cal/hour, 1:40 is 1500cal/hour.

https://www.youtube.com/watch?v=dsKjirJKSD4

The log from the Concept2 logbook for all three pieces also shows matching cal/hour:





Can you please help identify where I have it wrong?

angrytongan wrote: ↑

September 4th, 2020, 10:07 pm

Hi Allan,

Allan Olesen wrote: ↑

September 4th, 2020, 3:26 am

The calorie calculation is not the same as used by the PM. At pace 1:40, the difference is almost 300 kcal/hour.

[....]
1:40 is 1500cal/hour.

As I remember it, your diagram said 1200 when I wrote my post.

I agree to 1500.

And again: It is "kcal/hour" (or the more silly American "Cal/hour"). Never "cal/hour" unless you multiply by 1000.

angrytongan wrote: ↑

September 4th, 2020, 10:07 pm

I recorded this video of rowing for 1:00 at 2:00, 1:50 and 1:40. The monitor shows pace, ErgData shows cal/hour. Matching paces onto the chart shows the same cal/hour value - 2:00 is 1000cal/hour, 1:50 is 1200cal/hour, 1:40 is 1500cal/hour.

...

Can you please help identify where I have it wrong?

Your mistake it to assume that the way (k)calories are measured on the PM5 bears any relationship to the way (k)calories are calculated in the real world and by any other sports equipment.

They aren't. You get 300 (k)cal for free (just for sitting on the seat). You're assumed to turn calories into watts on the ergo at a 25% efficiency rate. You weigh in at 80kg.

http://eodg.atm.ox.ac.uk/user/dudhia/ro ... #section11

Also remember that pace is an inverse cube of power.
http://eodg.atm.ox.ac.uk/user/dudhia/ro ... l#section9

A 1:59.5 split is 205.1W
A 1:50.7 split is 258W
A 1:40 split is 350W

http://machars.net has some useful calculators. I got this graph of watts vs pace from there.

Hi Citroen,

Citroen wrote: ↑

September 5th, 2020, 4:17 am

Your mistake it to assume that the way (k)calories are measured on the PM5 bears any relationship to the way (k)calories are calculated in the real world and by any other sports equipment.

The chart displays the same thing as what is displayed on the monitor. It doesn't make any attempt to interpret it or map it to anything else.

Citroen wrote: ↑

September 5th, 2020, 4:17 am

A 1:59.5 split is 205.1W
A 1:50.7 split is 258W
A 1:40 split is 350W

The chart displays the same values, within a point or two:





I'm still not sure exactly what is wrong. I take the formulas from Physics of Ergometers, as you quoted and I referenced on the page with the chart. All the chart does is overlay pace, power, speed, cal/hour. These values match what is displayed on the monitor and logged in the logbook. Can you point to something specific that is incorrect, or give an example?

Citroen wrote: ↑

September 5th, 2020, 4:17 am

http://machars.net has some useful calculators. I got this graph of watts vs pace from there.

The chart matches this one, albeit with a reversed X axis and wider range.

Thanks for the website, I'll have a look at it.

I'm not sure what is wrong with the kcal/hr numbers either - they match up as close as possible to my Model C with PM3 numbers

robbiep wrote: ↑

September 6th, 2020, 3:48 am

I'm not sure what is wrong with the kcal/hr numbers either - they match up as close as possible to my Model C with PM3 numbers

The thing that's wrong with the (k)cal numbers is that they don't match any human being that uses a rowing ergo - they're not even close.

robbiep wrote: ↑

September 6th, 2020, 3:48 am

I'm not sure what is wrong with the kcal/hr numbers either - they match up as close as possible to my Model C with PM3 numbers

Once again:
When I wrote my first post, the OP's linked said approx. 1200 at 1:40. The correct number is approx. 1500.

The OP's link now says approx. 1500. So of course you don't see anything wrong.