Garmin Edge calorie estimate???

[jeltz]

Recently bought a Garmin Edge 605, so no HRM or cadence. Anyway on the last 2 rides 15 and 17 miles in a hilly area on the edge of The Mendips its telling me that I've burned off some 980+ calories.

Seems loads, surely that can't be right? Can it?

 

[jimboalee]

Are you puzzled it's too low or too high?

Garmin has a 'cookbook' roadload curve suitable for an average racing cyclist.
It's not a million miles away from a sports tourer with no mudguards.

The first calculation it makes is to calc Watts for the speed you are riding.

You should have entered in your weight and date of birth; and the weight of the bike.

The second calc is to modify for your age.

The third calc is to add or subtract Watts for the vertical speed up or down hills using the combined weight of you and the bike and the time it takes to change Elevation.


Garmin does not know the air temperature nor the windspeed. It assumes about 20 Deg C and still air. Neither does it know how you are dressed so assumes racing lycra.

When I adjust my own calc sheets to 20 Deg C, 0 windspeed and racing lycra, Garmin is within 2 % of my calcs for a FLAT route.

To compensate for the ammount of climbing on my roundtrip route to work, I enter 2.0% average gradient for the whole ride and my calcs are near 'cock-on' Garmin's number.

1000 kCals for a hilly 17 miles sounds OK in Garmin language.

If you want to know EXACTLY how many kCals you've used, it takes 12 years of building a spreadsheet that compensates for all conditions.

 

[jimboalee]

But, and it's a BIG BUT,,,,,

If you've been out for only 1 hour, you can divide that 1000 kCals by eight to arrive at a sensible nutritional reward value.

So it's 125 kCals for the first hour. Or two fingers of KitKat....

As the rides lengthen, it's a 'sliding scaler' until the Garmin figure can be eaten in its entirity. For me, this is at 220 km ( a reasonable Brevet 200 ) and the Garmin figure is 4500 kCals.

 

[jeltz]

Thank you, jimboalee, for that excellent response.

It struck me as high, that's all, but the likelihood that its reasonably close gives me even more incentive to get out there!

 

[Dave5N]

I've got a 705, as Jimbo said (or at least I think he did) the calorie counter talks bollocks.

 

[r0bbti]

But, and it's a BIG BUT,,,,,

If you've been out for only 1 hour, you can divide that 1000 kCals by eight to arrive at a sensible nutritional reward value.

So it's 125 kCals for the first hour. Or two fingers of KitKat....

As the rides lengthen, it's a 'sliding scaler' until the Garmin figure can be eaten in its entirity. For me, this is at 220 km ( a reasonable Brevet 200 ) and the Garmin figure is 4500 kCals.

Why do you divide by eight?
I am glad to see you talk my language and think in terms of Kitkats!

 

[jimboalee]

Why do you divide by eight?
I am glad to see you talk my language and think in terms of Kitkats!

It is because 1000/8 = 2FKK.

Or it used to be.
I've just been to confirm this and they are now 106 kcals per two fingers.

They must be smaller now FOR THE SAME PRICE !!

 

[jimboalee]

I've got a 705, as Jimbo said (or at least I think he did) the calorie counter talks bollocks.

No. The Garmin calorie counter is not talking bollocks.

It's major fault is it counts the calories of the work you do FROM THE START all the way to the finish.
Only after experience can you ignore the first 90 minutes worth because you know you ate that last night.

When Garmin's software people talk to sports nutritionists, the calorie counter will have a correction for 'Total time' and count slower for the first 90 minutes; and then revert to theoretical usage from then on.

This of course, will make the Garmin instruction manual even more compicated and incoherent, so I guess they won't do it.

Their minor fault is that they are assuming the users are lean strips of wind with no spare fat anywhere on their bodies ( typical cyclists ).
The slim svelte raceboys that we all are......