Machka 

I use an estimate of 100 calories burned for every 5 km.

So if I cover 5 km in half an hour I burn 200 cal per hour.

If I cover 5 km in 15 min I burn 400 cal per hour.

That fits with what Strava and MFP tell me.

gregf83 

Perhaps you're still asleep Since this thread appears to be descending into pedantry I'll offer a minor correction: 2x2x2 * 1/2 or 2x2

FBinNY 

yes, I was thinking half of and translated it wrong.

When I use the tablet, I get distracted by having to keep it from helping me, and stuff like this happens. BTW - you're also catching the same disease but it was a simple typo, not 1/2 or, but 1/2 of, or half of.

OTOH - it might be that the thread is jinxed.

DrIsotope

Not very close by any measure. "In the ballpark" is about as accurate as you can hope for. Heart rate is affected by, well, everything. HR can be used as a metric to monitor overall physical condition/conditioning, but not effort. If I'm going into overload, my HR won't raise above 140bpm (barely Z2 based on my LTHR) and will average ~115bpm. So I can do days of +200W average (~50kJ/mi) with a HR that is not at all indicative of the effort-- my HR should be significantly higher. Hell, a donut will raise my average HR for an hour, regardless of effort.

In my experience with several hundred rides with HR only, and several hundred more with power + HR, the two are not in any way related.

I also really don't see the reason for insisting on a difference between speed and pace-- a speed of 20mph is a pace of 3min/mi. They're just different ways of stating the same thing, at least for our purposes.

speed: rapidity in moving, going, traveling, proceeding, or performing
pace: a rate of movement, especially in stepping, walking, etc.

Semantics.

freedomnow2015

I know I did my research but the parameters for cycling have more difficult input compared to other sports. I currently use Samsung Health/GPS signal only. Not sure if it is accurate but it measure time, speeds, average speed, pace, average pace, distances.

freedomnow2015

By pace I mean minutes per mile, it is common in sports like running.

freedomnow2015

That seems like a nice rule of thumb however does it also match any fitness goals (like do you actually lose weight or maintain weight depends on your goals)?

I think your pace (if you do 5k in 1 hour) is 12 minutes per km, so (if you do 5k in 30 minutes) your pace is 6 minutes per km. This is what my OP is about, data that correlated calories to the pace/effort & distance & probably the cyclist weight.

gregf83 

You're right about the jinx.

I just substituted a multiplication sign for your division sign. I left the rest of the phrase as you wrote it.

freedomnow2015

I agree that pace is similar to speed. As a Threat Poster, I'm not interested in candance, that's not my OP which is pace/distance in calculation of calories burn (of course with consideration to cyclist weight although I am also concerned about the bike weight, do we add it to the bike weight?)

raceboy

Based on my totally unscientific calculations of me riding about 15mph and being about 180 pounds: 1 mile of cycling burns about 40 calories.

Uphill = a little more.
Downhill = a little less.
Faster = a little more.
slower = a little less.

You're welcome.

freedomnow2015

But I am not 180 unless you are talking to someone else.
How to estimate based on weight & distance then?
What you explain looks fair to me.

Viich

On a bike, weight only really matters on hills. Unlike running, your body doesn't have a vertical motion component. And once you start going around 20kph, wind resistance dominates other factors, so when going fast (by yourself), it is more burn by going faster, even same distance.

Machka 

Yes. Very well.

rm -rf

It's more like:
15 mph: 25-30 cal/mile
18 mph: 27-37 cal/mile

Climbing a moderate 4% grade: about 65-70 cal/mile.
downhill is "free" so climbing & descending the hill is around 35 cal/mile.

These numbers use the ballpark calories burned ratios: 24% useful work, 76% waste heat
These numbers "might" be 20% higher, if you are at the low end of converting calories into useful work: 20% useful, 80% heat.

Windy days, very rough roads, or drafting another rider can all affect the power needed. So calories per mile is probably just a ballpark number to get a rough idea of the whole ride's calories. It's interesting how few calories it takes -- bikes are very efficient.

My calculations:
The best estimates of calories are with a power meter. The power produced by a rider can be converted into calories.

This bike speed calculator gives quite good estimates whenever I've tested it, on flats or on climbs.
It says, for a 180 pound rider, flat road: on the hoods: around 120 watts, in the drops: around 100 watts. That seems pretty close to data from my rides.

120 watts for an hour is 432 kilojoules: 120*3600 seconds /1000. And 100 watts is 360 kilojoules.

Kilojoules is quite close to calories burned -- see the "converted into" link above.
So 120 watts is approx 430 calories per hour. (perhaps as high as
and 100 watts is approx 360 cal/hr.

At 15 mph, a mile is 1/15 of an hour. So the calories are in the range of 360/15 = 24 to 430/15 = 29
About 25-30 calories per mile.

.....
18 mph is about 140 watts on the drops, 190 watts on the hoods -- wind resistance goes up fast as speed increases.
That's 140*3.6 = 500 cal/hr. 1/18 is 27 cal/mile
through 190*3.6 = 680 cal/hr. 1/18 is 37 cal/mile.

.....
Hills
A 4% grade:
at 6 mph is 113 watts. 113*3.6 = 406 cal/hr. 1/6 is 68 cal/mile -- the mile takes a lot longer than on the flats.
at 8 mph is 153 watts. 153*3.6 = 550 cal/hr. 1/8 is 69 cal/mile -- the climbing takes a similar amount of energy either way. Interesting.

rm -rf

I never see cyclists using pace numbers. I suppose it's because riding has such a wide range of speeds, from 3 mph on a steep climb to 30+ mph on an all-out sprint. And, bike computers always showed speed and average speed, not pace.

Pace makes a lot of sense for runners.

Riveting

+1 for a power meter to tally the total calories without any guessing

A faster pace (aka speed) over the same course will mean greater wind resistance, which should mean more effort is required to ride the same course, compared to a slower speed/pace.

Drew Eckhardt 

My Garmin Edge 500 was off up to 100% on calories versus actual measured output.

Drew Eckhardt 

1 Watt = 1 joule/second, so 100W for 1 hour = 360,000 joules or 360kj. 1 Calorie = 4.2kj although cycling metabolic efficiency is never better than 25% so you can approximate 4 Calories in = 4.2kj out and round to 1 Calorie in = 1 kj out.

On "flat" terrain out-and-back using a power meter with +/-2.5% accuracy riding on my brake hoods I measure about 100W averaging 15 MPH for 360 Calories / hour and 24 / mile; 150W at 17 MPH for 540 Calories / hour and 32 / mile; and 200W at 20 MPH for 720 Calories / hour and 36 / mile.

YMMV.

Weight doesn't make an appreciable difference on flat ground.

An extra 50 pounds rounding to 23kg over 1 mile rounding to 1600 meters would add

23 kg * 9.8 m/s^2 * .004 Crr * 1600 m = 1.4 kj per mile = 1.4 Calories per mile.

10 pounds would be just 0.28 Calories extra.

caloso

To be fair, in my head I convert 20mph to 3 min/mile and 15mph to 4 min/mile because it makes it easier to estimate how long it will take me to reach my destination.

Craptacular8

Not familiar with Garmin Edge 500. Are you saying that system came with a chest strap heart rate monitor, and was still a 100% off based on some other "actual" measured output? If so, how did you determine that the other measured output was more accurate?

rm -rf

He also had a power meter to measure watts and kilojoules.

The heart rate based calorie counters are a rougher estimate of the calories burned.

On moderate to steep hill climbs, wind resistance is a much smaller part of the power -- most is fighting against gravity. So, knowing the bike+rider weight, the grade, and the speed, a fairly good power estimate during the climb is possible.

Drew Eckhardt 

Exactly.

Up steep hills, measured power output is about 10% over what you'd calculate on the back of an envelope only accounting for lifting bike+rider weight to the top, ignoring rolling resistance and aerodynamic drag.

Blue Sky

It all boils down to heart-rate, weight, age, and time. There are a couple of formulas - I use;
Men use the following formula:
Calories Burned = [(Age x 0.2017) — (Weight x 0.09036) + (Heart Rate x 0.6309) — 55.0969] x Time / 4.184.
Women use the following formula:
Calories Burned = [(Age x 0.074) — (Weight x 0.05741) + (Heart Rate x 0.4472) — 20.4022] x Time / 4.184.

IBOHUNT

There are inherent issues with whatever method you choose.
A power meter, while accurate to a degree is also inaccurate compared to another power meter.
As an example. I have a set of powertap pedals which read 5% higher than the powertap wheel. I had them both on using separate Garmins to record the data during an FTP test.
My Stages power meter ran 8% higher than the powertap wheel, again, running on the same ride with separate Garmins.

Moral of the story for me...
Use the data you get, from the interwebz, fitness tracker, powermeter or whatever and use the data consistently with a program such as myfitnesspal to track the food bits. You'll soon find out if the calories in versus the calories expended is working for you based on your belt. Adjust as needed. YMMV

dddd

I don't use sophisticated electronic aids so have not gathered any data myself. My Garmin seems to provide rough data when it comes to altitude so I don't put much weight in it's calorie reporting.


But physiologically, isn't there some sort of efficiency curve that charts changes in metabolic efficiency versus the level of intensity, and what does the curve look like?
I tend to eat like a horse after hammerfest training rides, once my appetite gets going. I force myself to eat a big bowl of microwaved (and seasoned/buttered/salted of course) vegetables early in my binge, a large variety including corn and spinach, etc.


As far as maintaining a desired weight, Chris Carmichael seems adamant about:
1) achieving fitness goals by training, and
2) achieving desired weight by eating "properly" for one's circumstances.


I believe that I have read his columns in Road Bike Action recently and he seems very consistent in what he recommends.