Road Bike, Cycling Forums banner

1 - 19 of 19 Posts

·
Diphthong
Joined
·
4,986 Posts
Discussion Starter · #1 ·
[Disclaimer]The search function isn't working well enough to help with this.[/Disclaimer]

How many calories per hour are burned while cycling? I did some googling and found some numbers for rather slow riding but wanted to get a better picture for how I ride. I found that riding 6mph burns 294 cal/hr and 9mp burns 444 cal/hr. Any idea what an 18mph average would be per hour?
 

·
Registered
Joined
·
21,525 Posts
Simple math

Bulldozer said:
How many calories per hour are burned while cycling? I did some googling and found some numbers for rather slow riding but wanted to get a better picture for how I ride. I found that riding 6mph burns 294 cal/hr and 9mp burns 444 cal/hr. Any idea what an 18mph average would be per hour?
Those numbers are way off, and anyway meaningless for regular cycling. Here's the formula:

calories/hr = [V*W(.0053 + %G/100) + .0083(V^3)]*7.2

where V is speed, W is bike + rider weight in lbs., and %G is grade in per cent. The factors listed here (0.0053 for friction + rolling resistance and 0.0083 for aerodynamic drag) are obviously not absolute. They will vary with efficiency of the tires and drive train, and with the aerodynamics of the bike + rider combination. Both of these assume a racing position on a racing bike. A clunker bike or a more efficient riding position will change these numbers, which are averages anyway. Power to overcome friction and gravity is proportional only to rider weight and ground speed. Power to overcome wind drag is proportional to the cube of the air speed. For reference, 1 hp = 2700 calories (because of human metabolic efficiency of 24%); 1 calorie = 0.276 watts; 1 hp = 746 watts. Here, all calories are kg-calories, or "food calories."
 

·
In need of sock puppet
Joined
·
9,420 Posts
Not to replace Kerry's data - My heart rate monitor provides a very rough number for caloric burn, based on (I assume) my weight, fitness level, and heart rate (they may factor in speed- the polar website probably lists all details). FWIW - I'm a fit middle-agd clydesdale, with a high max heart rate and low resting rate. It ranges from a low of around 5-600/hour at slow speeds to upwards of 1000/hour with hard efforts such as steep climbs or fast group rides.
 

·
Registered
Joined
·
896 Posts
you need to know power

I don't believe you can calculate calories consumed unless you know wattage for the time interval
 

·
Diphthong
Joined
·
4,986 Posts
Discussion Starter · #5 ·
I was english major so forgive me. Is the following correct where:

V = 16.5
W = 205
%G = 3 (estimate for flat-ish bike path)

Total of 1128.146 cal/hr.
 

·
For president!
Joined
·
7,802 Posts
Bulldozer said:
I was english major so forgive me. Is the following correct where:

V = 16.5
W = 205
%G = 3 (estimate for flat-ish bike path)

Total of 1128.146 cal/hr.
You're doing the math right, but I'm not sure what made you decide on a 3% average grade. If the route is very close to flat, try a .5-1% grade. The number is 520-650, much more reasonable.

A 3% grade is a noticeable, but not very steep hill. Probably enough to keep you in the little ring going 13-15 if you're not hammering.

Silas
 

·
Steaming piles of opinion
Joined
·
10,503 Posts
Bulldozer said:
I was english major so forgive me. Is the following correct where:

V = 16.5
W = 205
%G = 3 (estimate for flat-ish bike path)

Total of 1128.146 cal/hr.
(16.5*205*(0.0053+3/100)+0.0083*(16.5^3))*7.2=1128.146, so you've got the math right.
 

·
Registered
Joined
·
11,561 Posts
Bulldozer said:
I was english major so forgive me. Is the following correct where:

V = 16.5
W = 205
%G = 3 (estimate for flat-ish bike path)

Total of 1128.146 cal/hr.
Unless you're a real stud and then riding pretty hard or even flat out you're not going to be burning 1128 cal/hr, that would be somewhere around 325-350 watts.
 

·
Diphthong
Joined
·
4,986 Posts
Discussion Starter · #9 ·
SilasCL said:
You're doing the math right, but I'm not sure what made you decide on a 3% average grade. If the route is very close to flat, try a .5-1% grade. The number is 520-650, much more reasonable.

A 3% grade is a noticeable, but not very steep hill. Probably enough to keep you in the little ring going 13-15 if you're not hammering.

Silas
Good point on the grade. The difference between 3% and 1% is pretty big. I live in Colorado where you're either going up a hill or down a hill. This trail is one of the rare exceptions.
 
G

·
someone want to tell me what the little ^ bewteen the V and 3 is for. If it treat it as a multiplication i get close to 1500 and im assuming thats not right
v=19
w=173
%g=1
 

·
Registered
Joined
·
21,525 Posts
Completely wrong

jains89 said:
someone want to tell me what the little ^ bewteen the V and 3 is for. If it treat it as a multiplication i get close to 1500 and im assuming thats not right
v=19
w=173
%g=1
You are doing the math wrong. The "little ^" is the standard math term for exponentiation in Excel - if you read the text you would see that it is speed cubed, or speed raised to the power of three. Also, if you look at the equation, you will see that it is % grade/100. I didn't try every possibility, but I can't figure out how you got 1500. The answer for your numbers is 810 calories per hour = 225 watts (round numbers).
 

·
Registered
Joined
·
21,525 Posts
Bogus numbers!

High Cadence said:
Go to www.caloriesperhour.com and select the calculators. Then select bicycling, and put in whatever you know (two of either time, speed, and/or distance), and your weight. Seems to be fairly accurate from what I can tell.
Sorry, but this calculator site is WAY off. Typical of these generic things, it reads way high, just like most gym equipment and the phony numbers you get from HR monitors. The first clue is that the maximum speed it allows for cycling is 17.5 mph. The second clue is that it tells you that it takes over 260 watts (950 calories per hour) to go 17.5 mph. The number for this speed is over TWICE the actual calorie requirement. This site is completely useless for cycling.
 

·
Every little counts...
Joined
·
3,924 Posts
Another solution (with a power meter) is to transfer the Kilojoules work performed to Calories. As Kj to Cal are 4:1 but the efficiency of the body is 25%...you can proxy Kj to Calores burned.

Read 'Training and Racing with a Power Meter' by Hunter Allen
 

·
Registered
Joined
·
75 Posts
Thanks, this is very informative.

I assume all these numbers are for solo riding as group riding would dramatically change the aerodynamic drag.

Would it then be ok to use these numbers to estimate watts? Obviously it would only be a very, very rough estimation and would only work on flat ground with no wind but it should still give you a reasonable number, correct?

I assume the W number includes all weight (bottles, shoes, clothes, tools, helmet, etc.)

So if everything altogether weighs 164 lbs and I'm riding on flat ground and wind is negligible can I assume when I'm riding at X speed, I'm producing approx. Y watts?
17 mph ~ 110 watts
20 mph ~ 167 watts
25 mph ~ 300 watts
26 mph ~ 335 watts
27 mph ~ 371 watts
 

·
Registered
Joined
·
21,525 Posts
Correct crunching

stewie13 said:
I assume all these numbers are for solo riding as group riding would dramatically change the aerodynamic drag.

Would it then be ok to use these numbers to estimate watts? Obviously it would only be a very, very rough estimation and would only work on flat ground with no wind but it should still give you a reasonable number, correct?

I assume the W number includes all weight (bottles, shoes, clothes, tools, helmet, etc.)

So if everything altogether weighs 164 lbs and I'm riding on flat ground and wind is negligible can I assume when I'm riding at X speed, I'm producing approx. Y watts?
17 mph ~ 110 watts
20 mph ~ 167 watts
25 mph ~ 300 watts
26 mph ~ 335 watts
27 mph ~ 371 watts
Yes, your assumptions are right and you've crunched the numbers correctly.
 

·
Every little counts...
Joined
·
3,924 Posts
But when is this going to be accurate? Ever?

Maybe if you did an out-and-back on a relatively flat course with the same wind, holding the speed (no accelerations) over 2 hours then it might be accurate.

At this point, I'd just say that the calorie counter on your HRM is accurate 'enough'.
 

·
Diphthong
Joined
·
4,986 Posts
Discussion Starter · #18 ·
Spunout said:
But when is this going to be accurate? Ever?

Maybe if you did an out-and-back on a relatively flat course with the same wind, holding the speed (no accelerations) over 2 hours then it might be accurate.

At this point, I'd just say that the calorie counter on your HRM is accurate 'enough'.
Agreed. I'm just looking for an estimate for help in determining dietary intake of calories. Close enough counts for calories as well as horse shoes and hand granades.
 

·
Registered
Joined
·
21,525 Posts
Your choice

Spunout said:
But when is this going to be accurate? Ever?

Maybe if you did an out-and-back on a relatively flat course with the same wind, holding the speed (no accelerations) over 2 hours then it might be accurate.

At this point, I'd just say that the calorie counter on your HRM is accurate 'enough'.
HRM numbers are often off by 20% or more, since there is no way to predict any individual's calorie burn just from their heart rate. If you want more accuracy, you can use "air speed" in the aerodynamic term, and you can break up your ride into blocks to reflect climbing. Air speed is, of course, pretty hard to come by because wind speed reported by the weather report is measured 30 feet above ground and away from all buildings, trees, hills, etc. and you know that windspeed at ground level is zero. The point is that you can, on that flat and windless course, learn what a given level of effort is, and from that you can get a pretty good number. You can then apply this to the rest of your riding based on perceived effort or HR under controlled conditions. This approach is much more accurate than the bogus numbers coming from HRMs or Bicycling magazine.
 
1 - 19 of 19 Posts
Top