late

You heard it right...
it shows current output in watts, average and max. But the only number I want to see is the only one I need... how many watts did I burn in the exercise session.

I was all set to order one. Next year a new one is coming out that will do total watts.

What were they thinking?

supton

Take the average Watts, and multiple by time. That will give you Watt-hours, which is energy. Watt is a measurement of power, not energy.

Apus^2

Watts is a per unit time measurement. Just like you can't have total speed.

supton

1 calorie is 4.184J; 1J is 1 Watt*second. So, 1 Watt*second is 0.239cal. Only we humans run in kcal, and tend to measure in minutes or hours. So, 1Watt*minute is 0.01434kcal. But our muscles don't create power at 100% efficiency, so that kcal is kcal delivered to the bike, not what is burned from fat/muscle/carbs/etc.

Wikipedia has muscle efficiency running at 14 to 27%. That means you burn from 3.7 to 7.1 times that indicated kcal; but I'd think it far more, since the bike only measures power into it, while you have to hold onto the bike, expend energy to breath, etc. [I know you didn't ask for that much info, but I figured I'd toss it anyhow.]

late

in that case the power company owes me several grand..

nafun

The power company charges you for kilowatt hours, or the amount of energy used by a one kilowatt load in one hour.

Power is energy/time, so power*time is (energy/time)*time which equals energy.

Phantoj

Average watts X time in seconds will give you joules. It takes about a (kilo)calorie to do a kilojoule of work on the bike.

late

You guys need a humor transplant..

Phantoj

I was just thinking about this last night (as I was riding my KK trainer)... I wonder if the "average watts" is actually your average watts put out during the workout (i.e. total energy divided by total time), or if the computer just takes your average speed and does the conversion math on that. The latter would probably be a lot easier to implement, and would also be inaccurate.