Hi - love the podcast and the app. 5 stars all around. I’m trying to discern the correlation between kCals and kJ. I’ve created a spreadsheet with some metrics grabbed from a few sources, here: Calories vs Kj - Google Sheets Essentially, what I’ve noticed is that my kJ and kCal numbers can differ …

[image] Ivor_Griffiths: Essentially, what I’ve noticed is that my kJ and kCal numbers can differ wildly because you are using a Wahoo bike computer. Switch to another bike computer and discrepancies will vanish.

Yes, the conversion is roughly 1:1 as a crude approximation. So 1000 kJ measured by a power meter is roughly 1000 calories. this is the problem: [37%20PM] 593 calories and 1458 kJ is a completely wacky and wrong conversion. As I understand it, Wahoo bike computers sometimes report wrong conversi…

So yes, there is a standard conversion: 1 kJ = 0.24 kCal, or 1 kCal = 4.18 kJ. But by convention in cycling, kJ is used to measure the work done at the pedals – it is calculated by integrating all the instantaneous power measurements over the time you spent riding. By convention, kCal is used to me…

I’ve not yet come across an algorithm that uses HR to estimate calories burned that works with any accuracy. Generally, it appears when HR is used, most devices overestimate the calories burned. Until I learn of a proven methodology, I’ll stick with the 1:1 approximation. [image] Estimat…

[image] bbarrera: because you are using a Wahoo bike computer This is the correct answer to his specific question [image] Ivor_Griffiths: Essentially, what I’ve noticed is that my kJ and kCal numbers can differ wildly Your profile is private so I cannot pull exact numbers from your ri…

I figured out the issue… In my wahoo app, the HR zones we’re all jacked up. Basically they were somehow set so that my computer thought I was burning only calories ‘at rest’ under 125bpm. I fixed the zones and my calorie count was sane on my commute home. That said…I’m just going to operate on kJ f…

I think I am missing something here. It takes 4Kcal of energy to create 1Kj of work on the bike (assuming we’re 25% efficient), correct? But the Kcals we burn on a bike ride are not 4 times the number Kj’s of work we did right? I think I am missing something here. Any clarification would be grea…

The 1kJ calculated from the power measured at the power meter. But since we are ~25% efficient, the body has to expend 4 times that amount total to deliver that power to the pedals. So energy expenditure is 4kJ. Then you convert this to kCal which equals 0.956 kCal (1kJ = 0.239 kCal). The human body…

kCals vs kJ - why do they differ so much?

Ask a Cycling Coach Podcast

DaveQB June 11, 2019, 11:08pm 3

Just to be clear here, a kilojoule and a (kilo)calorie are both units of energy measurement. Like miles and kilometres are units of distance. You can convert between them.

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kCals vs kJ - why do they differ so much?

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