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Discussion Starter · #1 · (Edited)
I've recently started using a Garmin Edge 500 bundle, and am having some fun geeking out with the data. I haven't done a max or LT HR test, yet, but will in the next couple of weeks. One thing I've found is that the Calories estimate seems quite low, for me.

I'm 42, and a fit 6'-3" and 189 lb. I ride quite a bit, am one of the stronger local non-racers, but not one of the best climbers. My waking HR is 46 (was 42 when I was in my twenties), and I figure my LT is probably close to 160. I entered 8 for my Activity Level in the Garmin setup. Here's the data from my ride, today. I went relatively easy (mostly conversational pace) with a buddy for Laps (ride segments) 1 and 3, but Lap 2 was a climb of just over 2k feet in 12 miles that took me 55 minutes (click on Splits), at about the fastest I could do it, solo. The climb was between about mile 16.6 and the summit. Garmin's estimate was 731 Calories for that segment, but I would've guessed over 1,000. From the HR data, it does appear that I could've gone harder, earlier in the climb, but by the end I felt like I was at my highest sustainable output.
http://connect.garmin.com/activity/36751520

How else can I estimate my Calorie expenditure, and if it's low, is there some parameter in the setup of the unit or Garmin Connect, that I can use to get a better estimate on the data output? Is there some other software or spreadsheet that I can use to analyze the ride data? Any other comments? It's been several years since I've used a HR monitor at all.
 

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Discussion Starter · #3 ·
I might be able to borrow one, but until then, can I estimate power output and Calorie expenditure while climbing by using the total bike/rider mass and the rate of ascent? Below 10 mph, the aero drag component should be fairly small.
 

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Adorable Furry Hombre
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Garmin Edge units tend to be about 50-100% high in their calorie estimation.

Get a Ouija board, until you have a power meter. The Ouija board will be just about as accurate as a Garmin or a Polar rig at counting calories. The people who write calorie counters for gadgets are more concerned with ego massaging, than with producing realistic data. It is a "feature".
 

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Calculation

fallzboater said:
I've recently started using a Garmin Edge 500 bundle, and am having some fun geeking out with the data. I haven't done a max or LT HR test, yet, but will in the next couple of weeks. One thing I've found is that the Calories estimate seems quite low, for me.
This would be most unusual. Consistent reports here are that most HR based calorie estimations (Garmin included) are somewhere in the range of 30-50% high. If you're willing to take the time, you can break your ride up into pieces (climbs, flat sections) and input the numbers into analyticcycling.com. That will give you watts, and if you assume a 24% metabolic effciency, which is typical for a fit rider, you can multply your watts by 3.6 to get calories per hour. These numbers have been checked against power meters and the agreement is quite good.
 

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fallzboater said:
I might be able to borrow one, but until then, can I estimate power output and Calorie expenditure while climbing by using the total bike/rider mass and the rate of ascent?
http://analyticcycling.com/

fallzboater said:
Below 10 mph, the aero drag component should be fairly small.
True but it depends on the wind, which can have a sizeable impact on power-speed relationship, even when climbing steep grades.

e.g. Power required to ride at 10mph up 7% grade for 80kg bike + rider with a CdA of 0.32 and Crr 0.005; air density 1010 hPa:
3 m/s tailwind = ~ 265 watts
zero m/s wind = ~ 280 watts
3 m/s headwind = ~ 310 watts

3m/s wind = 6.7 mph

Reality is though that you'll ride at the power you can sustain, and the climb will take more or less time depending on wind conditions.

e.g. same rider at 280W will take:
4:04 per km at 3m/s headwind
3:43 per km with zero wind
3:32 per km with 3m/s tailwind

which means that mechanical work done could be anywhere from 59 - 68kJ per km depending on which way the modest wind might be blowing.

As for Calories metabolised, well that will then depend on your gross metabolic efficiency, so multiply kJ of mechanical work done by 1.15 +/- 0.1 to get an estimate range of Calories.
 

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Discussion Starter · #7 ·
Thanks for everyone's replies; that gives me some good stuff to play with while I'm supposed to be working, this week. ;^)
 

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The Garmin 500 is actually low. The other Garmin's (305 and 705) report more than twice as much for a given ride for me. Something is wrong with the weight unput calculations etc. It pretty much calculates the same calorie burn for 140lbs or 200lbs etc.
 

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Discussion Starter · #9 ·
TrainingPeaks Estimate

I just started playing around with TrainingPeaks, which gives me a RMR of 2,000 Cal, and for cycling at a METS of 12-16, it gives me 1,000 - 1,350 Cal/hr. Sound reasonable, for a fit 6'-3", 189 lb cyclist?
 

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fallzboater said:
I just started playing around with TrainingPeaks, which gives me a RMR of 2,000 Cal, and for cycling at a METS of 12-16, it gives me 1,000 - 1,350 Cal/hr. Sound reasonable, for a fit 6'-3", 189 lb cyclist?
Hard to say just based on knowing only that you're "fit" and without reference to duration, but those sound like solid training and racing outputs for a decent racer. I weigh about 7/8ths what you weigh and am a reasonably fit cat 2; adjusting those numbers proportionate to weight, and assuming kJ from my power meter to equate directly to calories (not a crazy assumption, but yes, an assumption), I can tell you that depending on ride composition, for me, a 4.5 hour ride averaging at the bottom of that range can be a very draining experience (and requires concentration, regardless), and I've pulled off about the top of that range for about 2 hours in a circuit race and been pretty happy to be done . . . . The last 80 minutes of my ride today was pretty steady at about 1,050 kJ/hour (so making the adjustments I assumed above, about 1,200 calories/hour "for you") and it's pretty clear based on rate of overtake that when I passed fit cyclists who I assumed not to be "serious" racers, that they were not making anything like that kind of effort.
 

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Nope

fallzboater said:
I just started playing around with TrainingPeaks, which gives me a RMR of 2,000 Cal, and for cycling at a METS of 12-16, it gives me 1,000 - 1,350 Cal/hr. Sound reasonable, for a fit 6'-3", 189 lb cyclist?

First of all, that estimate has a range of 35% (1000-1350) so that tells you right away how unreliable those numbers are. Second, 1,000 calories per hour is about 275 watts, so you'd be doing about 24 mph on the flats with no wind. 1,350 calories is 375 watts and nearly 27 mph. Were you going that fast?
 
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