Calories used cycling

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Calories used cycling

Postby themerlin » Sun Jan 15, 2012 10:34 am

Hi just looking at cyclemeter and it says my ride burned over 2600 calls, seems a little high to me. The ride was just under 70ks average about 32 kph and my weight is 103kg.
Do these apps tend to overestimate cals or is that figure ok.
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by BNA » Sun Jan 15, 2012 10:56 am

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Re: Calories used cycling

Postby Ozkaban » Sun Jan 15, 2012 10:56 am

Usually these things are complete fantasy. According to my android app, I burn about 33 cal/km. if it's a flat ride it's about double what my garmin 500 suggests (using the HRM, but still guess work), if it's very hilly it's still about 20% over.

I don't really trust the garmin in this respect, and the 'speed/distance' based ones are not even on the same planet...

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Re: Calories used cycling

Postby Phil » Mon Jan 16, 2012 2:32 pm

From a vague distant memory the equation for cycling cals burned is based on the METS which is basically a multiplier for your base metabolic rate based upon the degree of effort involved, pretty sure the ones commonly used for cycling relate to steel bikes without gears from 1950 odd era.

You can pretty much halve what they say and it will be close enough.
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Re: Calories used cycling

Postby BarryTas » Mon Jan 16, 2012 2:36 pm

themerlin wrote:Hi just looking at cyclemeter and it says my ride burned over 2600 calls, seems a little high to me. The ride was just under 70ks average about 32 kph and my weight is 103kg.
Do these apps tend to overestimate cals or is that figure ok.

depends on your HR and your HR zones
when do we stop for coffee???

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Re: Calories used cycling

Postby Alex Simmons/RST » Mon Jan 16, 2012 2:54 pm

themerlin wrote:Hi just looking at cyclemeter and it says my ride burned over 2600 calls, seems a little high to me. The ride was just under 70ks average about 32 kph and my weight is 103kg.
Do these apps tend to overestimate cals or is that figure ok.

Do the maths:

2600 Cal metabolised would equate to ~ 572 cal of mechanical work done (assuming 22% gross mechanical efficiency). 572 Cal = 2,390 kJ
2,390kJ over 2.1875hrs (70km/32km/h) = 1093 kJ/hr which = an average power of 304 watts (1,093,000 J / 3,600 seconds).

At 103kg that's nearly 3W/kg for 2 hrs. Not out of the question depending on how fit you are (that's pretty good going), although depending on terrain, conditions and type of bike, I'd expect you to go faster than 32km/h at that sort of power output.

In general, HR monitors and other bike computers are very poor at estimating energy metabolised. No more than some light comic relief.
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Re: Calories used cycling

Postby ldrcycles » Mon Jan 16, 2012 3:46 pm

I remember one ride where my HRM reckoned i had used over 6,000 calories :) . Possible, but how accurate it was i don't know or care. At one stage i worked out that the calories i was supposed to have burned on one ride was the equivalent of 140 weet bix :D .
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Calories used cycling

Postby themerlin » Mon Jan 16, 2012 7:26 pm

I agree it doesn't taken type of bike and sole/group riding into account.
I think I will divide it by 2 and not use it as an excuses to hit dominos
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Re: Calories used cycling

Postby Apple » Mon Jan 16, 2012 7:27 pm

themerlin wrote:I agree it doesn't taken type of bike and sole/group riding into account.
I think I will divide it by 2 and not use it as an excuses to hit dominos

I divide all my training by 2, running, cycling, swimming and Kayaking.
I have just started on Calorie King, I love it. :D
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Re: Calories used cycling

Postby toolonglegs » Mon Jan 16, 2012 7:43 pm

Also being your weight ... for me it is about (measured as Kjoules times 4 on a powermeter)
900-1200 Kcals per hour racing
700-900 Kcals per hour Endurance pace
500-700 Cruisy bunch ride pace
Things like Calorieking and Myfitness pal give you stupid amounts of credit for cycling exercizes.
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Re: Calories used cycling

Postby Apple » Mon Jan 16, 2012 7:50 pm

toolonglegs wrote:Things like Calorieking and Myfitness pal give you stupid amounts of credit for cycling exercizes.

That's for sure :roll:
That's why it's really hard to know how much I burned so for a 40 km ride with hills avg 25kph I would put in about 350 calories.
if I am gone for 7 hours at 22kph -25 kph I would put 700 calories. My garmin heart rate is not working. Calorie king goes crazy with the amounts on my rides, something like 1200 calories for a 70 km ride. I don't think so.
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Re: Calories used cycling

Postby Ken Ho » Mon Jan 16, 2012 9:22 pm

If you have entered your weight in kg, it will read out in kJ, not calories.
I reliably get about 3200 kJ for a solid bour, at 30kph which is 800 kCal or thereabouts, from Cyclemeter.
Don't know how accurate it is, but it's consistent. I was 80 kg when I setit up. Only 76 now, but have not adjusted it yet.
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Re: Calories used cycling

Postby PawPaw » Tue Jan 17, 2012 2:01 am

Phil wrote:From a vague distant memory the equation for cycling cals burned is based on the METS which is basically a multiplier for your base metabolic rate based upon the degree of effort involved, pretty sure the ones commonly used for cycling relate to steel bikes without gears from 1950 odd era.


I agree with this.

If you want to convert watts to Calories expended in generating those watts (excluding BMR), then multiply watts by 3.6. i.e. 150 watts * 3.6 = 540 Calories. This works because two factors essentially cancel each other out:
- joules to calories conversion requires dividing joules by 4.184
- body's efficiency is ~24%, therefore requires multiplying by 4.17.

Have a look at the last chart here
http://brisbanebike.blogspot.com/2011/07/watts-and-cycling.html
I usually work on 15-18 Calories per km for solo or bunch rides because my average is usually high 20s up to mid 30s, but mid 30s usually is with draft assist.
Hills in themselves are well above this rate but most of my rides are at least 75% flat.
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