I think it may be rather more sensible with the Turbo figures. For "moderate" it gives about 600kcals/hr
That seems a lot. Have i got the calculations wrong ?
600 kcal is 2520 kJ
One hour is 3600 seconds
That makes it about 700 W continual output for an hour
The human body is not 100% efficient at converting food calories into mechanical work. I remember estimates of the efficiency at about 25% for cycling, so the cycling power is more like 170W. I guess the rest is mostly heat.
yes, this causes confusion.
When you are using a powertap or other watt meter they are reporting output work done. When converting to food energy you multiply by about 4. It's easiest just to take the number of kJ and say that's the number of kcals.
Powertap reported 2400kJ for a 109km ride for me last weekend; this is about 2400kcal food energy.
Even then, I think this is going to be an underestimate because it's only measuring mechanical work that is delivered to the hub. Mechanical work that is simply used to move your legs, maintain balance, etc, is not included.
If the Livestrong numbers are a bit high, then they're high by at most 50%.