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JLLCJL85
02-09-2010, 12:11 PM
I am skeptical as to the accuracy of the calories burned on my Garmin 705.

I don't have a power meter, but I do use the HRM.

I generally subtract 30% and figure that to be about right.

Any thoughts?

CMENDERS
02-09-2010, 02:16 PM
If you dig around through some of the older posts you will see that this is a common issue with the 705. The addition of a power meter does not correct it. The two common solutions are decreasing your weight in the profile or reducing the calories burned figure by 30 to 40% as you are doing.

SMICKF
02-09-2010, 04:52 PM
I did a ride on Sunday, and my 705 says I burned 1,801 cals
I upload into Ascent, and the same ride in there says 3092 cals
The ride was a VERY hilly 26 miles at 2578ft of total ascent.

?????

SAEEDI
02-09-2010, 06:12 PM
Not sure if you're posing a question here. The 705 tends to overstate the caloric burn of a cycling activity. With that said, Ascent is showing an even greater discrepancy. I assume you are questioning the 705 vs. Ascent? Ascent performs its own calculations and you may wish to take that up on their forums (http://www.montebellosoftware.com/ascent_forum/index.php).

SMICKF
02-10-2010, 02:48 AM
Hi Steve,
Sorry for not being clear.

The point that I was trying to make, was that there are always discrepancies in calorie calculations. I think it's all to do the method of calc from one program compared to another. I don't believe there is a program that is 100% accurate. We are all striving for accuracy and absolute numbers, but I think that is a Utopian idea.

Personally, and I've said it on here within a different thread on calories, is that it doesn't really matter what the numbers are, providing the figures are comparable from ride to ride.

I am a member of the Ascent forum http://montebellosoftware.com/ascent_forum/? you will find me as "Mick F" on there. If you search through, you will find quite a few general queries regarding calorie calculations.

How do you know that the 705 overstates the calories consumed? Surely this is a figure that will vary from person to person and ride to ride. You never know, it may be understating my figures? Is this possible? I'm not saying one calculation is right and one is wrong, it's just that there are different methods of calculating it, and we pick out the figure that means what we want it to mean.

Sorry, I don't want to appear argumentative, please forgive me if you think I am.

Regards,
Mick.

IFLYSKYHAWKS
02-10-2010, 06:33 AM
To your point, my Edge 705 consistently reports fewer calories burned than what the following calculator reports which is a heart-rate based calculation:

http://www.braydenwm.com/calburn.htm

So, I tend to believe that the 705 is more accurate than we think...

ROBOTHEAD
02-10-2010, 06:40 AM
I understood the intent of your post, SMICKF, and agree.
The accuracy of the calorie algorithm isn't as important as its consistency so that trends can be clearly seen.
Unlike others on here, I have actually found that the Garmin estimate closely matches online calorie counters and past HR monitors I have used so I was never very concerned about all of this.
btw, from what I have seen, ASCENT looks fantastic.
Actually thinking about jumping back into the Mac world (used to be a hardcore fanboy going back to 1984) just to have it on hand.
Later . . . .

SMICKF
02-10-2010, 07:52 AM
Yes, Ascent is fantastic, and the best bit of software I've ever bought!

I've just been on another hilly today. The ride I referred to before was on a very heavy bike with few gears, and the ride today was exactly the same, but on my lightweight 30 geared bike.

Sunday's ride had 705 saying 1801c and Ascent 3092c - heavy bike
Today's ride has 705 saying 1811c and Ascent 2001c - light bike

I have my 705 set for 30lbs for one bike and 23lbs for the other.

The good thing about Ascent, is that it analyses the ride more fully than the basic system in the 705. Consequently, Ascent knew that I was having a hard time with the heavy and difficult bike and an easy time with the lightweight with all the gears.

I repeat, it was exactly the same ride - 26 miles - the heavy bike took a little over 3 hours, and today on the lightweight only 2 hours.

I think I believe Ascent more than 705, but so what? They are just numbers!

SEABEEGPS
02-12-2010, 12:59 AM
I may be the only one - but I ride with both Polar and Edge 705. And since 2.90 my calorie values are very similar. before that it was way off compared between the two.

Quite frankly - I'm more concerned with other figures than calories anyways.

ROBOTHEAD
02-12-2010, 11:55 AM
Agreed, SEABEEGPS, I am also more concerned with other numbers than calories but I do like to know cuz I divide 540 into the grand total to find the "Big Mac Factor" so as to give my wife a bit of perspective on some of my longer rides.
Even so, I'll come home beat up but feeling like a million bucks and say something like, "Babe! I just finished a 14 Big Mac ride!", hoping for a big kiss or, at least, a high five but usually get nothing but an eye roll and a groan.

CMENDERS
02-12-2010, 12:31 PM
Even so, I'll come home beat up but feeling like a million bucks and say something like, "Babe! I just finished a 14 Big Mac ride!", hoping for a big kiss or, at least, a high five but usually get nothing but an eye roll and a groan.

That is so true! My kids care more than the spouse usually does.

6THELEMENT
02-13-2010, 06:43 AM
I weigh ~170, but hve my unit set for 110 and believe that the figures it gives me like that are more realistic.

FAREASTJP
02-15-2010, 01:07 AM
Actually the Garmin devices if setup correctly (Age, weight, height, bike weight and resting heart rate) are very accurate. I've compared the results with other units and also a sports nutritionist and all the results are very close to one another. Of course as others have mentioned it's not 100% accurate but a 5% error rate isn't too bad.

For riders who are serious about the stats I suggest you weigh yourself before rides and update the data on the unit as being lighter or heavier will change the calculations

JAMIELAING
02-25-2010, 09:46 AM
I recently went on a walk with my 705 and HRM, just to get used to my new device and check out the baseline data. It was a moderately quick walk lasting an hour. I'm ~170lbs, the unit was running software version 2.40.

I was a little surprised to see the unit credited me with almost 1000 calories burned, which is clearly not possible.

May I ask a couple of questions?

1- Should the 705 be expected to calculate calories burned for a person walking or running as opposed to riding?

2- I've updated my unit software to v3.10. Should I expect better accuracy as a result?

3- Are there plans to address this issue in future unit software releases?

CMENDERS
02-25-2010, 11:27 AM
1- Should the 705 be expected to calculate calories burned for a person walking or running as opposed to riding?

2- I've updated my unit software to v3.10. Should I expect better accuracy as a result?

3- Are there plans to address this issue in future unit software releases?

1 - No. The unit is only set up for cycling.

2 - Not in my experience.

3 - No.

If you want the most accurate info for calories burned with ANY device you need to add a power meter and use the kilojoules burned. You can however lower your body weight on the Edge to get it closer to a correct figure.

KISERTN
05-02-2010, 03:48 PM
I've owned several Polar HRMs over the years and have never had cause to doubt their accuracy. I wore both my Garmin 705/HRM transmitter as well as my Polar HRM yesterday. The settings in my 705 were accurate (on the outleg anyway). The caloric expenditue numbers were WAAAYYYYYY off. The Garmin was 30-40% higher. On the way back I removed the weight of the bicycle from the Garmin and the Garmin ended up being approximately 10-15% off.

I don't undertand why my Polar has worked for years, doesn't ask me the weight of my elliptical curve machine/treadmill/etc., seems pretty accurate, and the Garmin is so off! Why is the Garmin making life so difficult by using distance/weight/etc ? (and failing at it)

I don't get it. I spent a fortune on my 705 and am greatly disappointed in its numbers. Those of you who wonder why couldn't the Polar be wrong and the Garmin correct, I can say that I am on a tight diet/exerise regime and I gain weight if I eat based on the calorie counts the Garmin puts out (meaning I eat relative to my exercise expenditure). Once I compared to the Polar and realized I needed to lower by 30-40% I was all good.

I'm very confident that the Polar is reasonably accurate and the Garmin is grossly off.

What I don't understand is why I read people saying that no one has a good algorithm. Clearly Polar has a good algorithm, but then they're using the HRM and evidently Garmin is not. Why? I'd gladly pay an extra $50 for them to DO IT RIGHT!

Sadly, I am considering switching to a Polar cyclng computer. Eventually, like others, I will not care so much about calories. But, for now, I care very much.

-Neil

REYES702
05-06-2010, 02:05 PM
I've owned several Polar HRMs over the years and have never had cause to doubt their accuracy. I wore both my Garmin 705/HRM transmitter as well as my Polar HRM yesterday. The settings in my 705 were accurate (on the outleg anyway). The caloric expenditue numbers were WAAAYYYYYY off. The Garmin was 30-40% higher. On the way back I removed the weight of the bicycle from the Garmin and the Garmin ended up being approximately 10-15% off.

I don't undertand why my Polar has worked for years, doesn't ask me the weight of my elliptical curve machine/treadmill/etc., seems pretty accurate, and the Garmin is so off! Why is the Garmin making life so difficult by using distance/weight/etc ? (and failing at it)

I don't get it. I spent a fortune on my 705 and am greatly disappointed in its numbers. Those of you who wonder why couldn't the Polar be wrong and the Garmin correct, I can say that I am on a tight diet/exerise regime and I gain weight if I eat based on the calorie counts the Garmin puts out (meaning I eat relative to my exercise expenditure). Once I compared to the Polar and realized I needed to lower by 30-40% I was all good.

I'm very confident that the Polar is reasonably accurate and the Garmin is grossly off.

What I don't understand is why I read people saying that no one has a good algorithm. Clearly Polar has a good algorithm, but then they're using the HRM and evidently Garmin is not. Why? I'd gladly pay an extra $50 for them to DO IT RIGHT!

Sadly, I am considering switching to a Polar cyclng computer. Eventually, like others, I will not care so much about calories. But, for now, I care very much.

-Neil


You and me both dude. I feel like weight x .60 is a bit too much based on how hungry I feel and how tired I am after I'm done riding. I might just lower it to multiply it by .40 but then I feel like I'm working with fictional numbers. I mean, you spend 600+ dollars on a machine that is supposed to tell you mass data but all the data is wrong and it becomes a waste of money.

I was thinking about leaving it as normal but just eating less than what my calorie expenditure says and just base it off how I feel. Rule of thumb is eat until you're not hungry, not eat until you're "full".

I;m so lost, I don't know what to do.

RFRUNS
05-09-2010, 06:20 AM
Add my tuppence to the calories-accuracy post. After an 80k/3.5hour ride my 705 showed 3506 calories, an Edge 500 showed 1775 calories. I had correct age/weight/resting heart rate in both. The speed data "looks" different, more "spiky" on the 500. If the 500 has a heart rate based calorie estimator that should be pretty easy to introduce into other devices/programs?

RACINGHEART
05-09-2010, 01:55 PM
Add my tuppence to the calories-accuracy post. After an 80k/3.5hour ride my 705 showed 3506 calories, an Edge 500 showed 1775 calories. I had correct age/weight/resting heart rate in both. The speed data "looks" different, more "spiky" on the 500. If the 500 has a heart rate based calorie estimator that should be pretty easy to introduce into other devices/programs?
From what I understand, I think the problem is that whatever the new algorithm is in the 500, if Garmin were to put it into a firmware update in the 705, they would have to pay some sort of licensing fee to Firstbeat Technologies Ltd (provided new HR "analysis solution" for the 500) for each 705 that was updated. Obviously, Garmin wouldn't want to pay for this and if they were to pass the fee on to the user for the firmware update, well I can bet that 705 users would be up in arms (especially since there are those questioning the 500's calorie numbers as well).

SMICKF
05-10-2010, 03:14 AM
I don't tend to look at the data within my 705, preferring to analyse it later on my MacBook using Ascent http://montebellosoftware.com

Ascent uses HR data to calculate the calories, therefore it should be more accurate than the 705 calculations. I wonder how Ascent compares with a 500?

LEOSZILARD
05-11-2010, 10:00 PM
From what I understand, I think the problem is that whatever the new algorithm is in the 500, if Garmin were to put it into a firmware update in the 705, they would have to pay some sort of licensing fee to Firstbeat Technologies Ltd (provided new HR "analysis solution" for the 500) for each 705 that was updated. Obviously, Garmin wouldn't want to pay for this and if they were to pass the fee on to the user for the firmware update, well I can bet that 705 users would be up in arms (especially since there are those questioning the 500's calorie numbers as well).

Exactly. Also keep in mind that in general heart rate based calorie calculation is not very accurate either. It might be more accurate than the 705's calculation, but neither give you an accurate value for calorie expenditure. Such calculations are best used as relative measures, i.e. used to compare one day's effort to another's. It's foolish to base your caloric intake on either what a Garmin or a Polar unit tells you.

If you want calorie calculations that are reasonably accurate, get a power meter. They'll be about as accurate as you can get. The only things they don't account for are inefficiencies unique to each person. Typically, in terms of power they're accurate to 2-5% (of indicated power). This means power meters then are typically accurate to 2-5% when calculating work (essentially calorie expenditure).

Of course none of this addresses the assumptions, approximations, and guesses that go into food calorie values. Accuracy is not the hallmark of those values.

UGASKIDAWG
05-14-2010, 10:03 AM
If you dig around through some of the older posts you will see that this is a common issue with the 705. The addition of a power meter does not correct it. The two common solutions are decreasing your weight in the profile or reducing the calories burned figure by 30 to 40% as you are doing.

Incorrect....if you have a power meter you know how much work (KJ) has been done so you know how many calories have been burned. Everything else is just a guess......

ROBOTHEAD
05-14-2010, 12:24 PM
Incorrect....if you have a power meter you know how much work (KJ) has been done so you know how many calories have been burned. Everything else is just a guess......

What CMENDERS may have meant is that the addition of a power meter will not correct the calories burned value as it is seen in the 705.

LEOSZILARD
05-14-2010, 01:33 PM
Incorrect....if you have a power meter you know how much work (KJ) has been done so you know how many calories have been burned.

No, that's not exactly true. You won't know how many calories were burnt do to inefficiencies in the process of doing work/maintaining other body processes. FWIW, calorie is fine as a work unit, but kilojoules is the more modern, more often used unit.

TECHVENTURE
07-12-2010, 02:52 AM
Hi everyone.
Unless anyone has done it already - couldn't find anything in forums - I am going to ride over 300kms across 3 days in France this week for charity. Will be using both Polar HRM and Garmin. Will post results next week..

TECHVENTURE
07-20-2010, 07:56 AM
Results are in. Over 3 days, 210 miles, hilly, flat, head winds, hot, cold, etc etc.............. Garmin reads 12% high.
That is it. :)

LML999
07-25-2010, 07:36 AM
I may be the only one - but I ride with both Polar and Edge 705. And since 2.90 my calorie values are very similar. before that it was way off compared between the two.

Quite frankly - I'm more concerned with other figures than calories anyways.

I'm a recent convert from Polar, have been wondering about using both. What do you use the Polar for?