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Round numbers

Bruce Rodgers said:
Any idea how many calories would typically be burned on a 25 mi ride assuming flat terrain and ideal conditions?
Some rough numbers (flat road, no wind):

10 mph, 15 calories per mile
15 mph, 20 calories per mile
20 mph, 30 calories per mile
25 mph, 45 calories per mile
30 mph, 60 calories per mile
 

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Kerry Irons said:
Some rough numbers (flat road, no wind):

10 mph, 15 calories per mile
15 mph, 20 calories per mile
20 mph, 30 calories per mile
25 mph, 45 calories per mile
30 mph, 60 calories per mile
Rider weight (and likely age) plays into it as well. Here is a link that adds weight into the equation. This chart is more in line with what my Garmin and Polar HRM's calculate. (Roughly 55-60 calories per mile at 18-20 mph . ( I tip the scales at 195-200 lbs.)

http://www.nutristrategy.com/activitylist.htm
 

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I think that the only way to calculate accurately is with a powermeter. Comparing calories burned with my Garmin 705 calculated, 25 miles, vs Powertap actual, there can be a 600-800 calorie difference (Garmin always reads higher). All dependent on hills and wind conditions.
 

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Way-off numbers

99trek5200 said:
Rider weight (and likely age) plays into it as well. Here is a link that adds weight into the equation. This chart is more in line with what my Garmin and Polar HRM's calculate. (Roughly 55-60 calories per mile at 18-20 mph . ( I tip the scales at 195-200 lbs.)
The numbers I quoted assume a 200 lb rider + bike combination, and use the very commonly quoted 24% metabolic efficiency for a fit person. 20 mph requires about 175 watts, so to get 55 calories per mile would mean a metabolic efficiency of 14%. This would mean a very out of shape couch potato riding a beach cruiser with underinflated tires.

The numbers you quote are rediculously high, and that topic has been discusse here repeatedly. 55 calories per mile at 20 mph would mean burning 1100 calories per hour, so a 100 mile ride would consume 5500 calories. I regularly do that kind of distance and only need to eat about 1600 calories, which, after including about 1000 calories from fat metabolis, would suggest that I am running a 3000 calorie deficit during that 100 miles. Not possible.

No HRM can calculate caloric expediture, and those that attempt to do so, routinely report numbers that are way high. Same with most exercise equipment found in fitness centers. Presumably this is to make the customer feel better about how many calories they're buring, but it has nothing to do with reality.
 

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Frog Whisperer
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back to the hour of sex...10 hours of riding...OH...it was the OTHER WAY AROUND?.......

Either way..it ALL depends on who's doing the WORK

For riding though sport tracks does a reasonable job of calculating from GPS data. Personal data and terrain data are both considered as well as speed and distance. If I cared about heart rate and rode with a monitor it would probably be more accurate
 

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Kerry Irons said:
So why is 600 calories per hour at 20 mph "no way"? Do you have some solid numbers to disagree with this rough estimate? You'll find it referenced in Bicycling Science, 3rd Edition, David Gordon Wilson, MIT Press.
If I rode 20, but I was talking 10 - even though I usually ride 25-40 most days.

"20 mph, 30 calories per mile" according to you. So if I rode average 20 mph (which I consider a pretty fast average speed) for 10 miles, ACCORDING TO YOUR QUOTE equals about 300 calories. If I got out (using a Polar HRM) and ride and average of 17-18 mph over 25 miles, I usually come in more along the lines of 1200-1500 calories. According to your figure, I'd burn more like 750. I think that data is flawed, and I don't care who your source is. If I was only burning 600 calories over a 20 mile distance at 20 mph, I'm going to quit cycling as a fitness tool.

And who rides absolutely flat, no wind conditions anyway? Come on...
 

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axebiker said:
If I rode 20, but I was talking 10 - even though I usually ride 25-40 most days.

"20 mph, 30 calories per mile" according to you. So if I rode average 20 mph (that's moving for 10 miles, that equals ACCORDING TO YOUR QUOTE about 300 calories. If I got out (using a Polar HRM) and ride and average of 17-18 mph over 25 miles, I usually come in more along the lines of 1200-1500 calories. According to your figure, I'd burn more like 750. I think that data is flawed, and I don't care who your source is.

And who rides absolutely flat, no wind conditions anyway? Come on...
I'd trust Bicycling Science BTW. It is a *very* analytical and thorough book.

Making a computation like you're wanting is a *very* tricky thing. Everyone's body is different, and reacts differently to different kinds of stress--flat conditions and no wind are ways of coming to a reasonable conclusion by eliminating as many variables as possibe. If vou ever study the calculus equations for air resistance and speed--they are a nightmare, even with simple systems without worrying abot pedaling technique or frame stiffness to worry about etc etc.


The other factor to remember is that a Calorie, the standard of unit used to measure food energy in the US, is in fact a "large calorie"....it is a standard convention that 1 Cal=1000 calories. 1 Calorie is a great deal of energy. 1 Cal is enough energy to raise 1 Kg of water 1C. 300 Cal is enough energy to boil 3kg of water starting from just above freezing. I don't have my copy of Bicycling Science handy--but I presume the figure cited by Monsieur de Irons is large calories not small calories.
 

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axebiker said:
If I rode 20, but I was talking 10 - even though I usually ride 25-40 most days.

"20 mph, 30 calories per mile" according to you. So if I rode average 20 mph (which I consider a pretty fast average speed) for 10 miles, ACCORDING TO YOUR QUOTE equals about 300 calories. If I got out (using a Polar HRM) and ride and average of 17-18 mph over 25 miles, I usually come in more along the lines of 1200-1500 calories. According to your figure, I'd burn more like 750. I think that data is flawed, and I don't care who your source is. If I was only burning 600 calories over a 20 mile distance at 20 mph, I'm going to quit cycling as a fitness tool.

And who rides absolutely flat, no wind conditions anyway? Come on...
You're basing this on the numbers from an HRM? I think it was Zinn who refered to them in his review as random number generators. They sinply do not have enough data to calculate Calories. With a working/calibrated power meter, you can get to within plus/minus 10-20%. Anything else (HRM, GPS, etc.) is just marketing. - TF
 
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