# Garmin Edge + Calories



## earth (26 Feb 2010)

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.


----------



## Mista Preston (26 Feb 2010)

it does do calories burned but i do not think its that accurate. I am not sure how it calculates it ?


----------



## gaz (26 Feb 2010)

It uses speed, time, and distance for calorie calculation.
Therefore not accurate..


----------



## Old Walrus (27 Feb 2010)

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.


----------



## jimboalee (27 Feb 2010)

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 ).


----------



## jimboalee (27 Feb 2010)

Old Walrus said:


> 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.



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 (23 Apr 2010)

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!


----------



## Sargent (23 Apr 2010)

I have the 605, and its crazy. 
I did 16 miles in 1 hour yesterday and it told me id done over 1000 calories. I think probably the max would be 700 for a guy, but thats guesswork.
Shame its not more accurate


----------



## Will1985 (23 Apr 2010)

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 (23 Apr 2010)

I like the high numbers, makes me think i need to eat more


----------



## Shady (24 Apr 2010)

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


----------



## amaferanga (24 Apr 2010)

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.


----------



## petercarson (24 Apr 2010)

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 (24 Apr 2010)

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.


----------



## fossyant (24 Apr 2010)

I really wouldn't bother with the cal. counter at all.... far more interesting data to be had out of the units.......


----------



## petercarson (25 Apr 2010)

fossyant said:


> I really wouldn't bother with the cal. counter at all.... far more interesting data to be had out of the units.......



Yep. I still think a 30 buck set of bathroom scales in a good way to figure out what's happening with your weight! I know that such crude measurements don't meet the high-science test, and I know you can buy a 300 buck set of scales that alleges to tell you how much of you is water, fat, muscle and...I dunno...poo, I suppose AND THEN transmit it wirelessly to something else. Go figure.


----------



## davidg (26 Apr 2010)

can I ask, for all the extra features the 705 has over the 605, I have a reasonable polar HR monitor (RS800cx) which does hr, alt, speed, cad etc and is really good, but being able to programme routes in and follow it doesn't. Would I regret getting the 605 and its lack of extendibility or are the extras on the 705 just not worth it in my position?


----------



## fossyant (26 Apr 2010)

I just went for the 705 from hantec - far cheaper than anywhere.....and narrows the price gap...... and built in HR is very interesting when comparing the 'spikes' on the routes.........


----------



## gb155 (27 Apr 2010)

I read that you need to times your weight by 0.65 and add that new, lower figure in, seemed MILES better yesterday when I had done it.


----------



## jimboalee (27 Apr 2010)

As I said, Garmin use a roadload curve for the average racing cyclist. Garmin know their physics so doing the compensations for hills is easy.

If a rider is using a powermeter, it is also a piece of 'consumer electronics' and not to be trusted. It is measuring the kW going through the crank or hub.

What ANY of the consumer electronics devices DON'T know is the weather.
This makes a big difference to calories used.

Sometimes I wish my Edge 605 had a thermocouple in it...

Garmin ASSUME the ambient air temperature is 20 C. If the ambient is 10, windchill makes it feel more like 2.5 C, and a human body works quite hard to combat this temperature. Like 5 cals/min, compared with the 2 cals/min actually pedalling the bike.

So if your powermeter calcs say you have been doing 1000 kCals/hour ( Tractive Consumption ), it will be more than this the cooler the air temperature is below 20 C.


----------



## jimboalee (27 Apr 2010)

What I do to crosscheck my Garmin is to adjust my calcs sheet to 20 C and zero wind.
They are similar ( +/- 2% ).

Then I punch in the Ambient air temp, wind speed and direction; and the distance and direction of the ride, and it tells me the total calories used.

If it's a hilly route, I enter a figure for climbing.
If I'm wearing long trousers, I toggle a parameter to tell the calcs to use a different coefficient of heat transfer through my clothing.

If the sun is shining, I toggle a parameter to tell the calcs to compensate for radiant solar uptake....


----------



## amaferanga (27 Apr 2010)

jimboalee said:


> As I said, Garmin use a roadload curve for the average racing cyclist. Garmin know their physics so doing the compensations for hills is easy.
> 
> If a rider is using a powermeter, it is also a piece of 'consumer electronics' and not to be trusted. It is measuring the kW going through the crank or hub.
> 
> ...



Calories from a power meter is still going to be closer than any HR or speed based calculation 99% of the time.


----------



## jimboalee (27 Apr 2010)

amaferanga said:


> Calories from a power meter is still going to be closer than any HR or speed based calculation 99% of the time.



A 'power meter' is a simple dynamometer.

The frame of the dyno' is clamped to the bike's rear dropouts.
The roller is effectively the wheel hub.

Inside, there is a magnetic brake and some strain gauges. The magnet pairs are on the outer hub and a floating part which is attached to the unit's frame by the strain gauges. 
The magnets try to stop the thing rotating and the strain gauges are stretched and change resistance in accordance with pull by the magnets.

The head unit is measuring the resistance of the strain gauges and a calibration polynomial calculates the Nm.

The rotational speed of the power-meter is measured and the formula is 

( Nm x RPM ) / 9549.3 to give kWatts.



Very simple, and not worth £800.


----------



## amaferanga (27 Apr 2010)

jimboalee said:


> A 'power meter' is a simple dynamometer.
> 
> The frame of the dyno' is clamped to the bike's rear dropouts.
> The roller is effectively the wheel hub.
> ...



Thanks for the irrelevant engineering lesson 

If its that simple why don't you make one? But remember it has to be reliable and require minimal maintenance - that's the tricky bit.

And like everything the cost is based on what people are prepared to pay, not how much the individual components cost.


----------



## jimboalee (27 Apr 2010)

amaferanga said:


> Thanks for the irrelevant engineering lesson
> 
> If its that simple why don't you make one? But remember it has to be reliable and require minimal maintenance - that's the tricky bit.
> 
> And like everything the cost is based on what people are prepared to pay, not how much the individual components cost.



I don't need to make one. No one does.

The simple 'freewheel down a hill' test will let you deduce your Road Load curve.
If there are some steep hills, you can include them on the spreadsheet.
If there is a gale howling, you can include it on the spreadsheet.
If there are icicles hanging off your nose, you can include the frost on your spreadsheet.

There is no necessity to own a powermeter or any calorie counting device. 
The 'calories' total from a simple spreadsheet will be within a box of Mr Kipling over a 100km Audax.

A more comprehensive spreadsheet will get the calories estimate within a finger of KitKat.


----------



## amaferanga (27 Apr 2010)

jimboalee said:


> I don't need to make one. No one does.
> 
> The simple 'freewheel down a hill' test will let you deduce your Road Load curve.
> If there are some steep hills, you can include them on the spreadsheet.
> ...



I didn't buy a power meter to calorie count though


----------



## jimboalee (28 Apr 2010)

amaferanga said:


> I didn't buy a power meter to calorie count though



So why did you buy one?

There a plenty of hills near Sheffield to do the costless 'freewheel test'.

There must be a hill near Sheffield that can serve as a hill climb time trial course to regularly gauge you progress.


----------



## davidg (28 Apr 2010)

can i ask with the 605, what do you need extra. memory card, map?

will just be road use to design my own routes and "save" some cash on sportives


----------



## jimboalee (28 Apr 2010)

davidg said:


> can i ask with the 605, what do you need extra. memory card, map?
> 
> will just be road use to design my own routes and "save" some cash on sportives



http://www.aukweb.net/

Follow the "GPS" link in the left index column.


----------



## jimboalee (28 Apr 2010)

When I ride a 25 miler, my Garmin says 1400 - 1600 calories.

My own calcs sheet agrees with 1450 calories.

The twenty five miler will take me just less than two hours. 
At that rate of forward propulsion, I'm going to replace 200 calories.

When I ride a 100km Audax, I'll replace 1250 of my calc' sheet predicted 3750 calories. 

When I ride a 200km Audax, I'll replace 4300 of the 7500 calories my calc' sheet predicts. 

When I ride a 300km Audax. I'll replace 10000 of the 12000 calories my calc sheet says. 

It is when I ride a 400km will I replace ALL the calories my calc' sheet predicts, 16000. 


I don't use Garmin as a calorie counter, but it was interesting to see that when it is set-up with sensible info about me and my bike, it agrees closely.


----------



## amaferanga (28 Apr 2010)

jimboalee said:


> So why did you buy one?
> 
> There a plenty of hills near Sheffield to do the costless 'freewheel test'.
> 
> There must be a hill near Sheffield that can serve as a hill climb time trial course to regularly gauge you progress.



Is this a serious question? 

If you think that time trialling up a hill once a month is as good as a power meter then there's probably nothing I could say to convince you otherwise.

In short, a power meter gives you an objective measure of your training. You can't fool yourself into thinking you're working hard like you can with an HR monitor or using a subjective measure like RPE. One of the greatest advantages of a power meter though is the fact that it gives you an objective means of quantifying training load.

Now what I'm not saying is that anyone NEEDS a power meter to train effectively. Just like you don't NEED a £2000 bike to ride fast. A power meter is just a tool that if used properly allows you to train more effectively. If not used properly its just an expensive piece of ballast.


----------



## stewlewis (9 May 2010)

Using SportTracks with your Garmin will provide more accurate (or just different?) calorie results, taking into account weather and wind too. Using the powertracks plugin will provide different results again.


----------

