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Discussion Starter · #1 ·
Completed a 115km ride on sunday, and after uploading my garmin data from my Garmin 500 I jumped on to the web site and searched for others putting up there times and info

The one thing i noticed was the that their calorie count were up to 2200 more than mine
so i compared their heart rate ave and found that they ave 10 to 20 bpm less than me for the same distance and very similar time
I admit that i do not know their height weight or age

But one person ave 136bpm for the 115 kmin a time of 4hrs 11min used 4500 calories
me ave 160bpm for the 115 km in a time of 4 hrs flat and used 2688 calories

the one thing that is not apples for apples is that i have the 500 and they used the 705

I have checked my set up on the garmin and it seems to be all ok is there something i missed or is the set up wrong ???

Twiggy

Before some of you jump on the band wagon lol I understand the calorie count is just a guide and that it is not 100% accurate but i just dont get the large discrepancy ??
 

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It's possible the Garmin 500 is more accurate than the 705. 2688 sound like a much more accurate number for the time/length of the ride. My old Garmin 305 generally doubles the amount of calories that my Powertap gives me - the 705 might use the same formula.

Edit: 2688 might be more accurate, but still sounds a bit high.
 

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Discussion Starter · #3 ·
fontarin said:
It's possible the Garmin 500 is more accurate than the 705. 2688 sound like a much more accurate number for the time/length of the ride. My old Garmin 305 generally doubles the amount of calories that my Powertap gives me - the 705 might use the same formula.

Edit: 2688 might be more accurate, but still sounds a bit high.

I am 5'10" and 176 pounds does that make it more acuurate lol with a max heart rate of 179 for the ride and ave 160 bpm

Twiggy
 

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The 500 IS more accurate than the 305. The 305 is off by a substantial margin. That said, the calorie count on the 500 isn't very accurate either.
 

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305 versus 500

I noticed the same thing after switching from the 305 to 500. I like the 305 calorie estimates much better!! :) It seems like I was averaging about 550 calories/hour on the 305 and about 150-200 calories/hour less with the 500 (with most parameters being equal). I have triple checked my set-up with the 500 (of course, since I want to burn more calories!!) ;) I'm figuring that the 500 is supposed to be more "accurate" in regards to calorie consumption and that my calorie expenditure was over-reported with the 305 (dang!). Interesting thing, my calories expended is higher when I don't use my heart monitor.
 

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705 does not measure ANYTHING to measure calories burned. The 500 uses HR to estimate it.

Hence the huge difference.
 

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JoelS said:
The 500 IS more accurate than the 305. The 305 is off by a substantial margin. That said, the calorie count on the 500 isn't very accurate either.
No calorie counter is.

That being said, the Edge 305/705 tends to be high by a factor or 2, in terms of reasonable output.
 

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I got some numbers for you. I calculated calories/hr from four of my rides w/ the Garmin 500.

per hour it comes out to be: 534, 571, 650 and 645.

Stats: 193 lbs, riding @ 16.2-17.5 mph (average speed of rides) for 1-2hrs.

When I calculate it out using calorie calculators online, my numbers are conservative.
 

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Just plug your .gpx files into SportTracks and you can get your calorie counts over 9000!!!

Seriously though, every different piece of software I plug my data into gives me a different calorie count. The Garmin one is always the lowest so I've gotta think they are at least a little conservative.

I've heard some speculation elsewhere that the Garmin software assumes 100% efficiency when in reality there's a good deal of variation in how people w/ the same statistics will burn calories at different rates doing the same activity. I have no clue if this is actually the case though.
 

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Marc said:
705 does not measure ANYTHING to measure calories burned. The 500 uses HR to estimate it.

Hence the huge difference.
While the 705 uses speed and distance coupled with your user profile info it’s certainly a crude calorie estimate.

For cycling only the edge 500 & 800 use a more accurate HR base calorie consumption but even with that you’ll most likely need to tweak your weight, age, bike weight and activity classification to best put yourself into a useable cycling event calculation of: 30 calories a mile.

30 x miles falls within an acceptable range and generally averages out over distance the additional forces placing load on you such as wind and grade etc. It works pretty well as a “point in time” calorie estimate but certainly does not reflect your personal Basal rate or the 12 to 24 hour “after burn” of your amped metabolic rate post exercise. And that’s where watching calories during a riding event to me is really is of little value.

Ultimately, for those who wish for better accuracy [not absolute but a good deal better than a HR strap] you’ll need joule from a good power meter.

Hopefully with Ant + mix and match, better head unit displays and functionality along with prices coming down a bit will find most if not all using some sort of power meter on board soon. Regardless, I’ll never expect perfect data and will continue to apply my personal experience ‘algorithm’ to normalize it all.
 

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DonDenver said:
While the 705 uses speed and distance coupled with your user profile info it’s certainly a crude calorie estimate.
A "crude estimate" it might be--but the result is still an utterly useless ego-food number that tells the user nothing due to the comical inaccuracy.

It doesn't matter if it takes more data points into account other than time elapsed or not-a useless number is still useless. It is even more of a joke on Garmin's part if they actually DID incorporate personal user data in the estimate...as they made a complicated math equation-that STILL is as useless as a Ouija board at guessing caloric output.
 

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Sadly, I have found that it doesn't matter what GPS, heart rate monitor you plan on using. The Calorie count is not an accurate measure of how many calories you burned it is a benchmark, a reference to use with subsequent rides of equal difficulty.

Sure it looks cool if a 50 miles ride burns 3500 calories or whatever but that shouldn't be a sufficent reason to go and eat like a horse for a day or two. Additionaly, if you use the same GPS watch for running and cycling be sure you have changed the settings. HUGE difference in "running" 50 miles instead of riding it.......
 

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Marc said:
A "crude estimate" it might be--but the result is still an utterly useless ego-food number that tells the user nothing due to the comical inaccuracy.

It doesn't matter if it takes more data points into account other than time elapsed or not-a useless number is still useless. It is even more of a joke on Garmin's part if they actually DID incorporate personal user data in the estimate...as they made a complicated math equation-that STILL is as useless as a Ouija board at guessing caloric output.
While I’ve already acknowledged in my post there are inherent inaccuracies with calorie data obtained with certain methods; I do not share your complete dismissal of this particular data point with respect to an overall training program. Actually, quite the opposite, as I know of few pro systems or coaches that don’t value an athlete’s daily calorie burn rate to help tweak training programs, rest states and dietary goals.

That said, with such simple point-in-time information based upon estimations provided by a Edge 705 there is nothing of value for the majority of cyclists other than is that particular number…whatever it is…consistent with other similar rides of mileage and effort.
 

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100%

SidNitzerglobin said:
I've heard some speculation elsewhere that the Garmin software assumes 100% efficiency when in reality there's a good deal of variation in how people w/ the same statistics will burn calories at different rates doing the same activity. I have no clue if this is actually the case though.
I think you have your numbers wrong. The human body (fit athlete) is about 24% efficient when you compare calories burned with watts delivered to the back wheel. A lot of these programs assume much lower numbers because they assume that you are not fit, but sedentary. If you look at the numbers that Bicycling magazine posts for their calories burned, they say that tootling along at 16 mph burns 40 calories per mile, when in fact the number is about half that. Most HRM or bike computer calorie calculators are 20-50% high.
 

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Kerry Irons said:
I think you have your numbers wrong. The human body (fit athlete) is about 24% efficient when you compare calories burned with watts delivered to the back wheel. A lot of these programs assume much lower numbers because they assume that you are not fit, but sedentary. If you look at the numbers that Bicycling magazine posts for their calories burned, they say that tootling along at 16 mph burns 40 calories per mile, when in fact the number is about half that. Most HRM or bike computer calorie calculators are 20-50% high.
Hehe, you're probably right. These are not my speculations though, was just regurgitating other theories I had read.

I don't see myself competing in any sanctioned events at anytime in the future and am not all that hung up on reducing my weight to achieve better performance on the bike. My goal is to sit at a fit and all around relatively well toned 6'2", 190-195lbs via a balanced, consistent, and sustainable exercise regimen and not stress myself out over caloric balances, so I don't have a whole lot invested in the accuracy of calorie counts personally. There's nothing wrong w/ wanting to be as lean as possible, just not one of my priorities.
 

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It is not a guide, it is hardly more then a wild guess.
twiggy73 said:
Completed a 115km ride on sunday, and after uploading my garmin data from my Garmin 500 I jumped on to the web site and searched for others putting up there times and info

The one thing i noticed was the that their calorie count were up to 2200 more than mine
so i compared their heart rate ave and found that they ave 10 to 20 bpm less than me for the same distance and very similar time
I admit that i do not know their height weight or age

But one person ave 136bpm for the 115 kmin a time of 4hrs 11min used 4500 calories
me ave 160bpm for the 115 km in a time of 4 hrs flat and used 2688 calories

the one thing that is not apples for apples is that i have the 500 and they used the 705

I have checked my set up on the garmin and it seems to be all ok is there something i missed or is the set up wrong ???

Twiggy

Before some of you jump on the band wagon lol I understand the calorie count is just a guide and that it is not 100% accurate but i just dont get the large discrepancy ??
 

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I had to put my weight on my polar cs600 at 85 kg. when I in fact weigh 120 (i know :-( ) That is based on the premise I got form magazines of roughly 700 kcal an hour when performing at 80 % of "workspace" between RHR and MaxHR. I havent seen any tabel with an average kacl use at different wights. Anyone seen that ?
 
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