Calories to Kj

[fmullin]

Knowing nothing, I've accepted the two numbers for calories and kilojoules given in teh iBike tool.
Looking at the ratios from several rides, I concluded that 1 calorie = 1.046 kilojoules.
But then I looked on the internet and found that 1 calorie = 4.184 kilojoules.
Your conversion is off by a factor of 4.
I suspect you know something I don't (not surprising since I don't know anything about this).
So what don't I know?

[coachboyd]

The average human body is about 25% efficient. Kilojoules is a measure of energy produced. So, if you produce 1000 Kj, at 25% efficiency that is 250KJ. 250Kj is equal to about 239 calories. This gives you a better idea of how many calories you need to add to your daily caloric needs to stay at a 1:1 ratio of calories in / calories out.