I've been looking at the specs for the 705 and it says it does not do heart rate based calorie estimation. Can anyone confirm this? Does it do any kind of calorie calculation? Seems a bit odd that it could navigate you around the world but does not have something as simple as a calorie counter.
Garmin Edge + Calories
- Thread starter earth
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Mista Preston
Veteran
it does do calories burned but i do not think its that accurate. I am not sure how it calculates it ?
gaz
Cycle Camera TV
- Location
- South Croydon
It uses speed, time, and distance for calorie calculation.
Therefore not accurate..
Therefore not accurate..
Old Walrus
Guru
- Location
- Hassocks, West Sussex
Before my old Polar HRM died I compared its estimation of calories burned (using heart rate) v. an Edge 705 using time/speed/distance. Result was that Polar was about half to 3/4 of the Garmin reading.
Garmin use a 'cook book' roadload curve to calculate calories. The 'cook book' curve is for a pretty aerodynamic race bike.
It uses the combined weights of the rider and the bike to calculate the additional calories when you climb a hill ( based on vertical speed ) or the calories to subtract when you freewheel down a hill.
It does NOT make adjustments for Air temperature of headwind. The calories it calculates is on the assumption the air is 20 C and there is NO wind.
Talking to Garmin and now knowing this, I have found the Cals calculator on the 605 quite accurate. To within 1.5% of my own calcs sheets when they are rebuilt for the correct type bike ( Cd of 0.85 ).
It uses the combined weights of the rider and the bike to calculate the additional calories when you climb a hill ( based on vertical speed ) or the calories to subtract when you freewheel down a hill.
It does NOT make adjustments for Air temperature of headwind. The calories it calculates is on the assumption the air is 20 C and there is NO wind.
Talking to Garmin and now knowing this, I have found the Cals calculator on the 605 quite accurate. To within 1.5% of my own calcs sheets when they are rebuilt for the correct type bike ( Cd of 0.85 ).
Old Walrus said:
Calories are a unit of energy. 1 kcal = 4186.8 Joules.
Everybody knows that a human being's heartrate is total unrelated to energy measurement.
There has been fierce discussion about Lactate Threshold and Watts production. They CANNOT be correlated.
petercarson
New Member
- Location
- Townsville QLD Australia
It is a shame that a device as insanely sophisticated as the 705, and its friends, can't make a half-sensible C calculation. If you trawl around the forums about this, there are all manner of opinions and work-arounds for this. They are mostly valid and will sharpen what is a very blunt tool, but it can never be accurate because it doesn't have enough physiological, biometric or environmental input, like temp and prevailing wind. That said, I think the Polar algorithm is a bit smarter, but anything that doesn't know power, expired CO2, BMR, Body Surface Area, (although it does know hight and weight so it might give it a stab), lean muscle mass and your VO2max just can't be accurate.
Those of us who would like to ride with a gas sensor strapped to our face and about 3Kg of other biometric equipment just have to find a cycling computer that can interpret it and 25 thousand bucks. You could hook it all up and velco a Laptop to your back, and that shouldn't take more than one hour to suit up and cost you 4kg in total! I can picture the cable-looms getting caught in the chain while you're riding the dge of a cliff. Whoops. On the upside, you would attract some attention.
Seriously, all cycle devices use various tricks to guesstimate C expense, but the Garmin can be relied on to be about the least accurate by consistently over-estimating, probably by 30-40%, since it doesn't use any real-time biometrics. Not even Heart Rate, and as jimboallee observes, that's not the real answer anyway.
It just looks at the workload suggested by the terrain-shape (altitude curve), how fast you go and how long you go for. It presumably accounts for sex (I don't mean if you stop for it, because you'd be on auto-pause and as high as your HR got, it doesn't "see" that: I mean if you're M or F) and some secret but static notion of your Basal Metabolic Rate based on height and weight.
Polar devices are a bit better if they have the feature which calculates your "training zones" based on a couple of sample warm-ups. Presuambly that's plugged into a kind of kindergarten VO2 max algorithm.
The only real value of the Garmin info is to trend your C expenditure; why anyone wants to do that is anyone's guess, but it will never even account for fitness as it doesn't use HR.
The next best thing is a power meter, but like a lot uf users, we amateurs really have no need of this degree of fanciness. Professionals and serious competitors might be able to convert all this into better riding but I'll stick to the things I need; an alarm clock, a bike and my Garmin705 with all its flaws. It's still fun to look at what you've done!
Those of us who would like to ride with a gas sensor strapped to our face and about 3Kg of other biometric equipment just have to find a cycling computer that can interpret it and 25 thousand bucks. You could hook it all up and velco a Laptop to your back, and that shouldn't take more than one hour to suit up and cost you 4kg in total! I can picture the cable-looms getting caught in the chain while you're riding the dge of a cliff. Whoops. On the upside, you would attract some attention.
Seriously, all cycle devices use various tricks to guesstimate C expense, but the Garmin can be relied on to be about the least accurate by consistently over-estimating, probably by 30-40%, since it doesn't use any real-time biometrics. Not even Heart Rate, and as jimboallee observes, that's not the real answer anyway.
It just looks at the workload suggested by the terrain-shape (altitude curve), how fast you go and how long you go for. It presumably accounts for sex (I don't mean if you stop for it, because you'd be on auto-pause and as high as your HR got, it doesn't "see" that: I mean if you're M or F) and some secret but static notion of your Basal Metabolic Rate based on height and weight.
Polar devices are a bit better if they have the feature which calculates your "training zones" based on a couple of sample warm-ups. Presuambly that's plugged into a kind of kindergarten VO2 max algorithm.
The only real value of the Garmin info is to trend your C expenditure; why anyone wants to do that is anyone's guess, but it will never even account for fitness as it doesn't use HR.
The next best thing is a power meter, but like a lot uf users, we amateurs really have no need of this degree of fanciness. Professionals and serious competitors might be able to convert all this into better riding but I'll stick to the things I need; an alarm clock, a bike and my Garmin705 with all its flaws. It's still fun to look at what you've done!
Will1985
Über Member
- Location
- South Norfolk
The 500 probably has a better calorie algorithm as it reads about 25% lower than the 705 in my experience. Adding a power meter does seem to improve figures a bit but the figures are still higher than the more detailed off the bike calculators.
gaz
Cycle Camera TV
- Location
- South Croydon
I like the high numbers, makes me think i need to eat more 
Shady
Active Member
- Location
- Isle of Man
I have an edge 500 myself and find that the calorie count is higher than my polar but I figure that my polar is high as well.
Its a nice figure to look at but in my experience its inaccurate - I tend to stick to the 10 calories a minute rought guide which works for me.
I was using the calorie figure exlusively and tailoring my calorie intake to that figure BUT I found that I wasn't losing any weight, so now I eat 2000 calories a day regardless of how much cycling / other exercise I am doing.
So far since switching to this plan I have started losing some weight !
Shady
Its a nice figure to look at but in my experience its inaccurate - I tend to stick to the 10 calories a minute rought guide which works for me.
I was using the calorie figure exlusively and tailoring my calorie intake to that figure BUT I found that I wasn't losing any weight, so now I eat 2000 calories a day regardless of how much cycling / other exercise I am doing.
So far since switching to this plan I have started losing some weight !
Shady
amaferanga
Veteran
- Location
- Bolton
If you have a power meter then you get a figure for work done in kJ. It turns out that when you account for human efficiency, etc. this figure is very close to kcal burned. This is AFAIK the only reliable way to get an accurate figure for kcal when you're out on your bike. FWIW I use a power meter with a Garmin FR310XT and on the few occasions I've done the comparison the kcal figure from the Garmin is about 50% under the kJ figure. Also, I did a hard 1h36min ride earlier this week and the total work was 1460kJ which equates to almost 1000 kcal in an hour.
It always amazes me when people complain about the kcal values on their Garmin - its little better than a good guess so if its within +/-50% of the actual value you should be fairly happy.
It always amazes me when people complain about the kcal values on their Garmin - its little better than a good guess so if its within +/-50% of the actual value you should be fairly happy.
petercarson
New Member
- Location
- Townsville QLD Australia
gaz said:I like the high numbers, makes me think i need to eat more
I'm with you! I switched from the Polar CS200 (which I still think is a fabulous bit of gear) to the 705 just over a year ago, and my appetite immediately increased! Amazing this technology. Mind you, I now weight 436Kg, but at least I have a cool cycling computer...
petercarson
New Member
- Location
- Townsville QLD Australia
It always amazes me when people complain about the kcal values on their Garmin - its little better than a good guess so if its within +/-50% of the actual value you should be fairly happy.[/QUOTE]
Dead on. Garmin, Polar, iBike; you name it. Some are good and some are good-er but they're all rough, and that's OK. We all know when we're working and most of us know what to eat, and how much. If it's weight-loss a rider is after then bathroom scales cost very little! Tailoting diet to meet estimated C expense will only achieve weight loss through co-incidence.
Dead on. Garmin, Polar, iBike; you name it. Some are good and some are good-er but they're all rough, and that's OK. We all know when we're working and most of us know what to eat, and how much. If it's weight-loss a rider is after then bathroom scales cost very little! Tailoting diet to meet estimated C expense will only achieve weight loss through co-incidence.
fossyant
Ride It Like You Stole It!
- Location
- South Manchester
I really wouldn't bother with the cal. counter at all.... far more interesting data to be had out of the units.......
