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BRADCONDER
01-31-2010, 02:54 PM
I just purchased an edge 500 last week and I love it. Only problem I have is the calories Iím burning during exercise seem very low. So far I have logged 5 or 6 rides and all being 25% - 50% under what the polar and online calorie expenditure calculators tell me i should have burned.

Yes i have added age, weight, height and fitness level.

Help please?? What is correct? Calorie calculators / polar or the Garmin

Example. I did my normal recover ride today. 2 hours of easy riding. Last 30 times i have done this ride I burnt 1000. Today was the first time with the Garmin and i reads 600 cals

RDONSON
01-31-2010, 04:48 PM
Even inputting all that personal data I don't think we can believe any of the calorie counters to any great extent. It would be interesting to know what formula and data the Edge 500 bases the calculation on.

As cyclists wouldn't we need input from a power meter to get a more reasonable idea of calories expended?

SAEEDI
01-31-2010, 05:38 PM
The Edge 500 uses the same Firstbeat method as the other Garmin devices such as 310XT and the 405CX.

BRADCONDER
01-31-2010, 05:54 PM
what is the first beat method?

i should be pretty easy to get close actually. all you need is a max HR, resting HR, weight, height, and activity level.

Has anyone else notice a difference in the garmins calculations? is anyone elses expenditure very low?

RACINGHEART
01-31-2010, 07:17 PM
what is the first beat method?

i should be pretty easy to get close actually. all you need is a max HR, resting HR, weight, height, and activity level.

Has anyone else notice a difference in the garmins calculations? is anyone elses expenditure very low?

Excerpt from Garmin's press release back in Sep 09:

"When paired with a Garmin heart rate monitor, Edge 500 tracks the micro changes in a userís heart rate and uses that detailed information to better calculate the number of calories burned. In developing Edge 500 and its heart rate-based calorie computation, Garmin worked with Firstbeat Technologies Ltd., a technology company based in Finland. Firstbeat is an industry leader in heart rate analysis, specializing in developing user-centered software solutions for heart beat signal analysis in exercise and sports, weight management, and stress monitoring applications."

Granted, these calorie numbers need to be taken with a grain of salt, but I think at least the 500 is probably more realistic than the numbers spit out by the 705, which has the notorious reputation for overestimating calories by upwards of 40-60%. Unfortunately, from what I understand, since Garmin has to pay a licensing fee for the algorithm for each unit, I'm guessing it will never make it into a future 705 firmware update.

CMENDERS
01-31-2010, 07:31 PM
I have both the 705 and the 500. Along with them I have PT so I actually use the Kilojoules instead of calories. With the 705 I would have to use 60% of the calculated calories to get close to the Kj figure. With the 500 the calories are actually coming up short. To compensate for this I have found that if I increased my weight entered in the 500 by about 8% I had similar figures.

Hope that helps.

BRADCONDER
02-02-2010, 04:26 PM
ok. i have taken 4 rides all with the same average HR (132bpm) and compaired the calories burnt per min

Garmin 1, 10.97 calories per min (I increased my weight to 100kgs for this one!)

Garmin 2, 7.76 calories per min (@80kgs)

polar 1, 13.83 calories per min (@73kgs)

polar 2, 12.4 calories per min (@73kgs)

at this rate if i enter my weight as about 140kgs the claorie counter might just come out right. shame thats double my actual weight

KENNASTER
02-04-2010, 07:16 PM
I have both the 705 and the 500. Along with them I have PT so I actually use the Kilojoules instead of calories. With the 705 I would have to use 60% of the calculated calories to get close to the Kj figure. With the 500 the calories are actually coming up short. To compensate for this I have found that if I increased my weight entered in the 500 by about 8% I had similar figures.

Hope that helps.

Nice analysis. I would agree that the kilojoules measured by the PT would be the most accurate for cyclists. Nice to have a side by side comparison.

ANDERSONBILL
02-05-2010, 10:29 AM
My 500 does not come anywhere close to the calories I should be burning. I believe the firmware is not using the parameters that I input, but is rather using the defaults. Male, age 35, weight 150 fitness 4. I am Male age 63, weight 183, fitness 8. I have tested my theory by setting the 500 back to these settings and exercising. The result was that the calories burned were within 2% of what was shown with my actual settings. I'd suggest you all try this test and put your setting up to my numbers and see if there is a change.

XCAMRIDER
02-05-2010, 01:39 PM
I'm curious to see what people are using for their caloric consumption? It seems it can vary widely between devices not to mention what level of exercise you are riding at.

Just curious.

MARC.LAGESSE
02-06-2010, 10:15 AM
what is the first beat method?

i should be pretty easy to get close actually. all you need is a max HR, resting HR, weight, height, and activity level.

Has anyone else notice a difference in the garmins calculations? is anyone elses expenditure very low?

I went away from my Garmin 705 to a Polar becasue the 705 over estimated calories.
Recently bought the 500 because I thought they fixed the problem with the 705 type GPS... Now the 500 under estimates the calories... So back to the Polar I go...
To be honest, I'm not impressed, how hard can it be to calulate the calories burnt???

TECHATHY
02-06-2010, 10:57 AM
Without a power metering hub very difficult. The difference between my road bike & my commuter bike going into a 5mph headwind on the flat is 120w for the road bike & 165w for the commuter, however if I get to a 5% gradient in still air & ride up it at 10mph the road bike requires 197w while the commuter needs 202w. So if you've not got a power meter that little lot needs to be taken into consideration & some how averaged out.

Even with a power meter it's not simple as the device has no way to take into consideration how well or otherwise I've maintained my bikes drive system, how warm or other wise I've dressed both of which can have a noticeable effect on the calories you burn.

RDONSON
02-07-2010, 12:47 PM
I posed this question to a cycling friend of mine who has advanced degrees in exercise physiology and works in the cardiology unit of a local hospital.

His concerns with trying to calculate calories from heart are:
- as a person gets better conditioned, the heart rate for a given work load decreases.
- even within the same workout there is a situation known as cardiac drift. That is, as your blood volume decreases due to sweat loss and urine production, your heart rate goes up even with the same workload
- in cycling, for the same workload, if you ride with a higher cadence you produce a higher heart rate
- as a rule when climbing, which is one of the higher work loads you can produce, you do not generate your highest heart rates because of cadence issues.

After talking to him I can't help but conclude that calories from HR is at best a rough estimate no matter how sophisticated the algorithm used and how much personal data you provide that algorithm.

BRADCONDER
02-07-2010, 01:31 PM
Thansk every one and thansk RON for taking the time to ask your friend.

I have got the calories up a little by putting my weight up to 140kgs!!! But after reading RONs post i have decided i dont care anymore. Im joking my self if i think burning calories is the problem anyway. Its got a lot more to do with what im actually eating. Ie sugars crap! Time to review the diet :(

DEDOL@B
02-16-2010, 10:09 AM
My 500 does not come anywhere close to the calories I should be burning. I believe the firmware is not using the parameters that I input, but is rather using the defaults. Male, age 35, weight 150 fitness 4. I am Male age 63, weight 183, fitness 8. I have tested my theory by setting the 500 back to these settings and exercising. The result was that the calories burned were within 2% of what was shown with my actual settings. I'd suggest you all try this test and put your setting up to my numbers and see if there is a change.

Could you explain step by step how you do it?

ROBERTDAINES
02-16-2010, 10:53 AM
- as a rule when climbing, which is one of the higher work loads you can produce, you do not generate your highest heart rates because of cadence issues.

I don't really understand this statement, can you elaborate? For me at least, climbing always produces my highest heart rates.

Thanks,
Bob

RDONSON
02-16-2010, 11:52 AM
I don't really understand this statement, can you elaborate? For me at least, climbing always produces my highest heart rates.

Thanks,
Bob

I think what my friend was saying is that most of us climb at much lower cadence. For example, I'm a Clydesdale and 60-70 RPM is a good cadence for me climbing. If you're like Lance and climb at 90-100 RPM or higher then you may indeed see your higher heart rates.

ROBERTDAINES
02-16-2010, 12:47 PM
Ron, thanks for your reply. I am curious, if you analyze your rides, is your heart rate generally higher or lower on climbs vs flats? I thought that one of the arguments against using speed to determine calories burned was that on climbs, where you are burning the most calories, you are actually at your lowest speeds.

Cheers!

RDONSON
02-16-2010, 08:12 PM
Well, first let me make it clear that I don't have any degrees in exercise physiology, biomechanics, etc. That's my friend. I'm just an engineer interested in those fields. I've learned a lot from him but my knowledge is very meager.

For me my heart rates are generally highest on slight, short inclines when I treat them like an interval or busting a gut on a flat doing interval training for TTs. On long or steep climbs I generally find a rhythm that works for me and my heart rates are pretty steady around 85% of my max HR. I don't know if that a survival technique on my part or what. :D

I can't imagine using speed as a way to calculate calories burned. It would seem like there are too many variables unaccounted for.

AMAFERANGA
02-17-2010, 02:58 AM
Its the effort you're putting in and the Watts you're producing that primarily determine HR, not cadence.

THRASH155
02-17-2010, 06:51 PM
I have the same Problem. The Difference between the FR60 and the Edge 500 is roughly 200 calories for the same loop and effort/time.ect.. ect. It wouldn't be a big deal but on longer rides of 4 hours It would be a Huge Deal.

NAFTALIM
02-20-2010, 11:08 PM
Yes, the differences are absurd. On more or less the same ride of 78K, with the 705, I get 2,900 calories and with the 500 I get 965? On a 3 hour ride I would expect to be burning more than 965 calories.

Can someone from Garmin please explain this issue?

Thanks

RACINGHEART
02-21-2010, 02:53 PM
Yes, the differences are absurd. On more or less the same ride of 78K, with the 705, I get 2,900 calories and with the 500 I get 965? On a 3 hour ride I would expect to be burning more than 965 calories.

Can someone from Garmin please explain this issue?

Thanks

I'm not from Garmin, but I was curious, as ANDERSONBILL stated earlier in this thread, whether there is a problem with the 500 retaining the Activity Class setting that the user enters. The manual doesn't really explain how this value is used, but if it works any way similar to the newer Polar units, it should have an effect on the calorie calculation. So the questions that arise are 1) is the user entering a truthful activity class value? and 2) is the 500 actually retaining this number or resetting back to the default number? As ANDERSONBILL suggested, maybe try riding the same courses at a similar efforts, but changing the Activity Class values, and see what sorts of changes in calories is reported by the unit.

Also, I believe Garmin realized that their 705 over reported calories by a lot so they made the effort to correct it by working with Firstbeat Technologies Ltd from Finland, even though all these calorie algorithms still need to be taken with a grain of salt.

I'm also curious what devices people are using to get what they think is their "real calorie expenditure" in order to compare to the 500's numbers? Other Garmin units, Polar units, power meter kJoule numbers, etc?

THRASH155
02-27-2010, 12:06 PM
I use several To Verify Calorie Expenditure. Trainingpeaks.com, Livestrong.com, Current Garmin FR60 User, ect. They all seem to be pretty close or within 5% which I can live with.

I use the Calorie reminder on long training rides to remind me to either drink or eat something. So for me its pretty important.

THRASH155
03-01-2010, 10:37 PM
Here is a Two Tracks from My FR60 and Edge 500, It was pretty cool since they both synced up with my GSC10 and HRM Strap.

Fr60
http://connect.garmin.com/activity/25819557

Edge 500
http://connect.garmin.com/activity/25898426

about 600 calorie difference. :(

PPRESING
03-02-2010, 01:21 AM
My experience with edge 500 calorie calc is not bad so far. With latest firmware 2.20 obviously calculation has been improved. I compared the same ride with approximate the same time and avg heart rate. I compared Edge 500 with Polar RS 800 CX.

Result: Polar, 1550 kcal, Garmin 1460 kcal!!!

* avg heart rate at Garmin ride was 1 beat/min lower than at Polar, but ride with Polar took me 3 min less time. I think those two results are more than comparable, I realy don't have much complains about calorie calculation.

Maybe if I put on couple of kg at Garmin personal settings I could get even closer,...

THRASH155
03-02-2010, 07:44 PM
Went for another Training Ride Tonight and got the same Results. Cross refernced with Livestrong.com(613Kcal) and TrainingPeaks.com(626Kcal) and my FR60(630Kcal) was used at the same time as the Edge 500 which calculated the ride at (418Kcal).

Based on my previous Ride and this one the Calorie Calculation is off about 33%. Its hard to image the Firstbeat algorithm is off that much.

These are based on a 161# Activity Level 8 Meh.. Go figure.

SWISSPADDY
03-15-2010, 12:31 AM
Hi all , has anyone been able to resolve the issue w/ the calorie count calculation with the edge 500. I bought it last week in replacement of a 705 i lost in amtb bike race . I did 2 routes i do regularily on a sat and sunday . The calorie total was off by 60% . I had old data from my polar to check which calc's using VO2 max . W/ the 705 it was over stating initially but resolved it self . I also adjusted the activity level to see if that would help to no effect . I have read in other posts that some edge 500 users are lowering the actual body wgt to reflect an correct reading . Thank you in advance for any advice in resolving this issue . Kind regards Michael

BRADCONDER
03-15-2010, 03:05 AM
Hello All

Well its been about 6 weeks since i first posted about the low calorie count that the 500 has been giving me. i found one answer to the problem. put my weight up to 140kg (from 70kg!) i have now put it back to 70kgs. it still gives me low reading but i just dont worry about it now. sorry i wish i could help more

brad

D0NSUT
03-16-2010, 01:09 PM
I'm getting intermittent results. Some rides the KJ and Cal are within 10 but then sometimes they are way off like my last ride. Not really sure why this is. I just go off my PowerTap KJ's.

Here's some info from my last ride.
Cal (Garmin500) - 1036
KJ (PowerTap) - 1251

SWISSPADDY
03-19-2010, 02:00 PM
to anyone who has had calorie count issues , i would appreciate if you could work out what your calorie per minutes are for the rides you have done with low counts. i am a 79kg 36 yr riding b/t 8/12 hrs aweek. my intial ride was 1h40 at 75% of max w/ 740m, of climbing. the garmin 500 gave me a calorie per min of 10 cals a min (avg speed for theride 28kmph, distance 44kms)when i set my parameters at 140kgs, activity level at 3 and replicated the same ride the garmin 500 gave me 12 cals per minute. from older polar data i have for the same rde i dshould be getting apprex 16/17 cals a minute. i am curious if this 10/12 cal a min ranger is a default level in the program . if others are getting similiar please let me know . u can reply to this thread.

THEDREWJOHNSTON
03-29-2010, 10:39 PM
to anyone who has had calorie count issues , i would appreciate if you could work out what your calorie per minutes are for the rides you have done with low counts. i am a 79kg 36 yr riding b/t 8/12 hrs aweek. my intial ride was 1h40 at 75% of max w/ 740m, of climbing. the garmin 500 gave me a calorie per min of 10 cals a min (avg speed for theride 28kmph, distance 44kms)when i set my parameters at 140kgs, activity level at 3 and replicated the same ride the garmin 500 gave me 12 cals per minute. from older polar data i have for the same rde i dshould be getting apprex 16/17 cals a minute. i am curious if this 10/12 cal a min ranger is a default level in the program . if others are getting similiar please let me know . u can reply to this thread.

Has anyone tried entering their weight in lbs rather than kgs? Perhaps the algorithm is using lbs and not successfully converting from kgs first. That would explain why entering 140kgs instead of 70kgs seems to work (1kg=2.2lbs). My understanding is that the rule of thumb is that a 70kg rider riding in a group at 30kph burns approx. 770 KCals per hour.

CJLIVINLIFE
05-09-2010, 06:23 PM
I just finished a 4hr ride and it seems like the Garmin 500 Edge is showing what I should have burned in one hour for the whole ride. It showed 695 calories for the whole 4hrs. When I calc out what I should have burned per a few different web sites it should have been around 2700 calories. This is a bit crazy if you have to double your weight in the darn thing to get the right amount of calories burned. I have changed the activity number and it does seem to default back for every new ride. I wonder if Garmin will ever correct this with updated software...........
Thanks

PEPERINO1966
05-27-2010, 03:03 PM
I've a bit of doubt about the algorithm used:

Lap 1
km 70,28.... time ..... 2:28:35....... AVG sp: 28,3....... total ascent 78 (without cardio) cal 2505

giro 2
km 67,70... time ...... 2:22:10 ....... AVG sp: 28,6 ...... total ascent 79 (with cardio) AVG bpm 132 cal 917

How does it calculate the calories consumption?

also: when I ride down (and stop to pedal) the calories continue to increase

CJLIVINLIFE2010
06-11-2010, 06:28 PM
I agree that the calorie consumption seems to go to the default no matter what you put in there. The only difference I have noticed is that now if you take that same ride without the HRM see how many calories you burn. I am showing a huge difference and both are very very low or very very high!!!

KARLMARSH
11-02-2010, 05:53 PM
I believe that some of the Edge 500 units are defective when it comes to Kcal. This is because I have 2 different units with the exact same settings, same firmware and paired to the same hear rate monitor and one gives me about 1200 Kcal for a 30 mile ride and the other gives me about 800Kcal for the exact same ride. All other data fields come out exactly the same. I plan on contacting Garmin about this issue.

KINBOY
11-03-2010, 08:51 AM
I have chimed in many times about calories, I will avoid a long discussion by saying that even with a power meter, heart rate and speed input, you cannot get within 20% of actual values for more than 5% of the population. Toss in efficiency of drive train and the person...

If you toss in an actual blood measurement in a lab 2 times a year and full work up and use that to calibrate your HR you MAY be able to get values that are close for you for 80% of your riding. Monthly testing with specific zone readings, I would say you could keep within 95% accuracy most of the time.

Oh ya, stick around the lab for 6-48 hours (there are different schools of thought on the caloric expenditure AFTER working out)

Polar may give you more consistent readings and results BUT by no means more accurate.


KIN

TERENCEKIRK
12-01-2010, 06:58 PM
I recently got an Edge 500 and became curious about how the calorie calculation was done which led me to this thread. It seems to me there are 3 components to the energy expended during exercise:

1) Potential energy gained = mass x g x elevation gained (mass here is total: body + bicycle + clothing etc)

2) Resistance to motion from rolling friction, windage, losses in gear train etc. These types of losses generally go up as the square of the velocity.

3) Energy over and above 1) and 2) to keep the body functioning.

I cannot think of any way to account for 2) except by having some sort of watt meter, but I took a shot at trying to estimate 1) and 3).

I got some info off Wikipedia and did some calculations on the 3 rides I have done since I got the Edge 500. Assuming 1 Calorie = 4186 Joules, that the energy conversion efficiency of the body is 25% and that the body burns 300 Calories / hour during exercise, the results came up as follows (Calculated as a % of Edge 500):

Ride 1 (14.4 mls, 1079 ft, 1:19): 99.6%
Ride 2 (19.1 mls, 2608 ft, 2:12): 125.6%
Ride 3 (12.4 mls, 922 ft, 1:10): 103.1%

I then tried the calculation on some other riders who ride the same trails as me and have posted their results on the web site and for 3 rides I selected at random from one specific user I got 109%, 107% and 98%. For two different riders I got 67% and 71% respectively (I donít know any of their masses, so that may account for the difference - Iím using a total mass of 200lbs/91kg).

Obviously this is back of the envelope stuff, and the size of the data set is too small to be meaningful, but it looks like Iím sometimes in the right ballpark. I'd be interested to hear any comments on the assumptions / logic.

As many people on this thread have noted, trying to get a true reading of calories consumed is probably a foolís errand; my interest is in how Garmin calculate their value.

RICHARDS_C
12-07-2010, 03:15 AM
I have a new edge 500. Firmware is 2.4. Depending on the ride, the calories consumed are between 35 and 45% of my Polar (F55) watch :confused:

I am 97 kg and after a 3 hour race with a average heart rate of 83% of max, the Garmin says 1646 Calories (9.6 calories/min)... Epic Fail! This is with an activity class of 8 and having entered my weight as 210 Kg!

I think anybody using imperial units ... miles/ft etc may be getting reasonable results, but anybody trying the metric equivalent, just gets rubbish. I seem to remember a mars lander crashing for the same reason after a collaboration between the Americans and Europeans got the unit conversion all mixed up.

Please Garmin ... respond and fix ... You are quick when its an easy answer, but the moment the there is a suspicion that the units programming is a little f$%ked you are never around to offer any advice or help.

The rest of the market is catching up and its becoming general knowledge that your support is non existent should there be an issue. Cycling forums reach a wide target ...

NU52NTJ
12-07-2010, 07:07 AM
I have downloaded the same ride from my Edge 500 on to 3 different sites and get totaly different calorie readings.
Garmin Connect 803 cal.
Sports TrackLive 2684 cal.
Ride With GPS 2914 cal.
Both the latter figures are from exported TCX file from GC.
I also downloaded to R W GPS directly from the 500 and got the same result.
I would suggest that the fault is with GC not the Edge 500.

RICHARDS_C
12-08-2010, 02:27 AM
Had a look at the tcx files. The Edge 500 does put a calorie count in there, which is too low.

Sports Tracks lets you recalculate the calories. I did a short (30 min) ride a while back and Edge says calories = 239. Recalculate on ST and I get 527.

239 * 2.2 = 527. The conversion between pounds and kilograms is ~2.2, so I think the problem is fairly obvious.

Can anybody confirm that the edge gives reasonable results if they use imperial (pounds, inches etc) units?

FRIARFOLD
12-08-2010, 06:48 AM
I have mine set to lbs but the calories are still way too low (2 hours mountain biking and only 700 calories total). I am doing the same circuit tonight and am going to try entering my weight x2.2 i.e. normally 134lbs I will try 295lbs. Will post results tomorrow.
Just to note that mine is set to display;
Distance, speed, height, weight - imperial units
Altitude, temperature - metric units

More info - these are the average calories per min for my last 19 rides, some of these were at an average of 18mph so not exactly a slow pace, do these seem low? 134lb (61kg) male, ride average 8 hours per week, have set activity level at 7
1 6.7
2 7.7
3 7.6
4 9.3
5 9.8
6 6.1
7 6.9
8 9.4
9 7.7
10 6.9
11 7.2
12 8.9
13 8.8
14 6.5
15 6.0
16 7.9
17 8.3
18 9.2
19 6.1


7th Jan 2011 update to the above, setting my weight at 2.2 x actual i.e 300 lbs instead of 136 lbs gives me a much better result. A 17 mph ride now gives me an average of 12 calories per minute rather than the previous 7/8. As other users have said it would be nice for someone at Garmin to admit there is a problem even if there is no solution yet.

HOWARDSTOTLAND
01-05-2011, 08:15 AM
I agree with you 100%. I have been using the NEW Forerunner 410 which uses the same formula for calorie calculations. The calories shown are usually 25 to 50% of what I believe is correct. I know it is some formula based on heart rate but the calculations are much too low

RUNBIKELIFT
01-07-2011, 10:00 PM
I just got the Forerunner 410 after using Polar for 10 years, and I also think that the calorie count is very low compared to what Polar used to tell me (off by about 200 calories or so)

YOUNGBLOOD2
03-29-2013, 09:17 AM
RDONSON ... Its all in how you climb. High cadence can raise your HR. Trust me. We all have different builds and physiology. Your greatest efficiency for hill climbing may be with heavier gearing at a slower cadence. Or, it may be at a higher cadence with lighter gearing. It seems to me that on your longer climbs your focus (like me) is more to make the climb rather than to race up it. You may be using lighter gearing and pushing your cadence up a bit, but I'll bet you are travelling at a much (much) slower speed than when you push over the short inclines. You are in "complete the climb without killing yourself" mode. Yes, you are preserving yourself. And one of the things you are preserving is your expenditure of energy. But drawing the conlcusion that higher cadence means lower HR is faulty in my estimation. Yesterday, I was on the trainer doing 90 RPM with a gearing that had my HR in the bottom of Zone 4. Then I took it up to cadence of about 100 rpm for 1 minute at the end of the interval and my HR zoomed to the bottom of Zone 5. But, in this scenario, I was not "settling in" for a long climb.

YOUNGBLOOD2
03-29-2013, 10:19 AM
For the others commenting on comparison of calorie burn to the Garmin Forerunner and Edge ... I have to ask how you are determining which is the accurate measure? I believe that you start from an assumption of what the correct colorie burn should be and conclude that the Garmin devices estimate too low. What if it were the other way around? I think that we tend to bias our judgment toward the results that tell us we are burning more calories. And then we judge the results that tell us its lower than we like as incorrect. And, on another point, I have to wonder which of these algorithms take into account basal matabolism and if that is subtracted out. And I wonder if that might account for some of the differences.

IBOHUNT
03-30-2013, 06:46 PM
For the others commenting on comparison of calorie burn to the Garmin Forerunner and Edge ... I have to ask how you are determining which is the accurate measure? I believe that you start from an assumption of what the correct colorie burn should be and conclude that the Garmin devices estimate too low. What if it were the other way around? I think that we tend to bias our judgment toward the results that tell us we are burning more calories. And then we judge the results that tell us its lower than we like as incorrect. And, on another point, I have to wonder which of these algorithms take into account basal matabolism and if that is subtracted out. And I wonder if that might account for some of the differences.

I rode yesterday for 1:42:35 with an average power, using a powertap hub, of 203Watts. Garmin Connect says I burned 800 calories.
If I take the formula that's all over for converting watts into calories I get

203W * 6155 seconds / 4.184 / .25 (efficiency)* .001 = 1194 food calories.

1194 - 800 = 394 calorie difference. Quite substantial.

VOICERESPONSE
03-30-2013, 08:12 PM
You know all the formulas for figuring Calorie burn and Calorie intake are still based on averages. What I've never seen published is the deviation of the data. So even if you get all the devices and formulas to agree, it might just be that we individuals may actually vary be 15 to 20 percent in burning Calories. Also, I doubt we all absorb the same amount of Calories from food, nor do I think every equal measure of the same food contains the same Calorie content. So just be consistent with how you track your Calories. If your Calorie count vs what's actually happening with your body don't agree, then adjust. It's the trends you're interested in, not the bean counter numbers.