So, the kJ number shown on a PT or SRM... how is this calculated? I'm assuming for a one hour ride at 150 watts
150 watt seconds X 3600 = J / 1000 = kJ
this would come out to 540 kJ, or 130 calories
Um, that seems a little low to me. So, is this the total energy into the bike? It seems very low to be the total calories burnt, or the total energy into the pedals or I just screwed something up. So, what's going on here? What is the kJ number actually representing?
As an interesting aside I've found that the kJ value seems to be about the number of Calories I would "normally" eat after a ride.
The human body is approx. 25% efficient in turning food calories into pedal calories, so you need to eat 4 Cal for each kcal expended on the bike. Since each kcal is approx 4 kJ, the number of kJ expended roughly approximates the number of Cals of food that must be eaten to replenish the body.
So, the kJ number shown on a PT or SRM... how is this calculated? I'm assuming for a one hour ride at 150 watts
150 watt seconds X 3600 = J / 1000 = kJ
this would come out to 540 kJ, or 130 calories
Um, that seems a little low to me. So, is this the total energy into the bike? It seems very low to be the total calories burnt, or the total energy into the pedals or I just screwed something up. So, what's going on here? What is the kJ number actually representing?
As an interesting aside I've found that the kJ value seems to be about the number of Calories I would "normally" eat after a ride.
Thanks all, Justin
Remember that kJ on the bike is *roughly* equal to calories since most people are *roughly* 25% efficient on a bike.
And one hour at 150 is basically soft-pedalling at best, so...
