Unit Conversion

[chewie]

Digging through the forums, I've found a formula for converting pace to watts. Does anyone know the formulaic relationship between watts and calories that C2 uses? Using joules=watts*seconds and calories=joules/4184 isn't getting me the right answer.

[johnlvs2run]

calories/hour = Kcal/hr = watts x 4 x .8604 + 300

[Citroen]

Digging through the forums, I've found a formula for converting pace to watts. Does anyone know the formulaic relationship between watts and calories that C2 uses? Using joules=watts*seconds and calories=joules/4184 isn't getting me the right answer.

All the maths you need is here: http://www.atm.ox.ac.uk/rowing/physics/ergometer.html

You get 300cals for free. Try it, set the PM2/PM3/PM4 to calories, pull the chain just enough to register a low power stroke every 5 seconds.

[Bob S.]

All the maths you need is here: http://www.atm.ox.ac.uk/rowing/physics/ergometer.html
You get 300cals for free. Try it, set the PM2/PM3/PM4 to calories, pull the chain just enough to register a low power stroke every 5 seconds.

It is interesting that the document obtained from the above URL has this disclaimer from C2:

The 300 kC/hour has always been our best approximation for keeping alive and awake and going through the rowing motion at a reasonable stroke rate on an erg with the flywheel removed. This was arrived at from internal experiments and observations, data from Fritz Hagerman and studies done at Ball State. We never meant to suggest that one can consume 7200 kC a day by just sitting still, and we certainly apologize if there was any miscommunication on our part.

Since the 7200 kC (sic) is about 5 times a reasonable average basal metabolism rate it seems to include an awful lot for just going through the motions of rowing. Hikers lugging 60-70 pound backpacks on mountain trails generally figure to need about 6000 Calories a day. Of course the actual work time is probably about 1/3 of the whole day, but they are working a lot harder than 3 times what is done by someone sitting on a erg going back and forth with no wheel spinning.

I don’t really see any point to having the calorie function on the monitor when it is this arbitrary.

Bob S.

[chewie]

Thanks. The 300 was throwing me.

[jamesg]

Strangely enough, and despite the thing being called an ergometer, the kCal readout is the only indication, however arbitrary and indirect, of the amount of work actually done. Though of course to multiply average Watts by time is very simple; it just gives such depressingly low values. **
More interesting than the 300 which has its logic and can be subtracted if we wish, is the factor 4; it means we are considered as fuel cells with 25% efficiency. Better than most engines, but nowhere near a power station. And is the real value the same for everyone?
For a certain period, I tried a "training" method based on the kCal readout: 500 a day. It worked just as well as any other system. Can't get any simpler than that, but it does get a bit stressful if you don't have much time.

** 200W for ½h is 0.1 kWh. At the price I see in my electricity bill, that's the classic 2 cents worth.

[Citroen]

For a certain period, I tried a "training" method based on the kCal readout: 500 a day. It worked just as well as any other system. Can't get any simpler than that, but it does get a bit stressful if you don't have much time.

I see a lot of the non-rowers in the gym, they jump on, slap the damper up to 10, set the display on calories and row until they've done 100 of the mythical units. There may be some value in that - at least they're doing some rowing. (Probably, not enough to light a lightbulb.)

[emptybeer]

Seems like there is some angst about the "bonus" 300 C/Hr. Despite its arbitrary nature, adding the 300 C seems to be consistent with other workout equipment (treadmill, bike, elliptical) for me for a given effort based on heart rate.

[Ducatista]

I don’t really see any point to having the calorie function on the monitor when it is this arbitrary.

If people are erging to lose weight, a calorie function, however arbitrary, can be a powerful motivator.

Better than that, IMO: calories are the finest increment on the monitor. I can hold a given time/500m till the cows come home, even with indifferent technique. But maintaining a consistent calorie readout is a tough (and engaging) test of stroke consistency.

The anti-calorie bias has always seemed a bit snobbish to me, which is unhelpful to newbies and noncompetitors. Who cares if the monitor is counting sheep, as long as people are moving their butts back and forth on the rail?

[ancho]

Hi, Duc:
How would you set the display on your Triumph, if you could?
(Sometimes I'd like te have a HRM on the bike... )