Garmin Edge + Calories

[petercarson]

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]

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]

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]

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]

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]

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]

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.

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

 

[jimboalee]

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]

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.

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]

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]

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.

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

 

[jimboalee]

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]

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]

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]

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.