Spartan420

Just did a 6 hour TrainerRoad session.

6 Hour Ride
67% intensity factor
117 watts avg power (yes, I am weak)
88 RPM avg cadence
113 avg HR
40 Year Old Male
138 pounds

My smart trainer has a power meter. My Garmin just goes by HR and maybe cadence.

According to the power meter (Kinetic inride) and TrainerRoad, I burned 2500 calories. According to the Garmin, I burned 1000 calories .That makes eating enough to recover after the ride a bit challenging to figure out I have no idea how many calories I just burned.

gregf83 

Go with the 2500 from the powermeter. The Garmin is likely based on the notoriously inaccurate HR.

DrIsotope

The 2500 should be fairly close.

That is definitely the definition of a Long Slow Distance (LSD) ride.

Seattle Forrest

Power meter for calories, always.

OBoile

As others have said, go with the power meter. It is actually measuring the work you're doing where as the other is just an estimate.

asgelle

Don't forget that without measurement of the rider's efficiency, converting from work performed to calories consumed is also just an estimate.

DrIsotope

But it's quite a good estimate, because metabolic efficiency falls into a pretty narrow range for humans. And it's not like it's that hard to say, "Oh, the power meter said 2,000kJ for that ride, but I'm trying to shave some weight, so I'll treat it like it was 1,800 and eat accordingly."

OBoile

As DrIsotope says, it's a very good estimate as the the main input, work performed, is known. Estimating that is the hardest/least accurate part.

caloso

702 watt hours = 2527 kj. Assuming 25% metabolic efficiency, 2500 kcal is right in the ballpark. Go with that.

colombo357

You did a 6 hour ride on a trainer?

I enjoy training indoors but 2 hours is my max.

Spartan420

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i did do it on the trainer with no music no TV, nothing just the TrainerRoad app.

exmechanic89

I know wow, my hat's off to you, OP. I have a pretty high tolerance of monotony but I don't think I could do 6 hours on a trainer.

zacster

I did a 3 hour session during the "Tour of Sufferlandria" and I could barely move afterwards. I never wanted to see another Sufferfest video again, nor get on the trainer again. I can't imagine doing twice that.

I always figure 400-500 calories per hour, so 2500 is about right.

smashndash

On a somewhat relevant note, does anyone know how accurate Strava calories are? I watched a video that compared Strava power to real power and it was supposedly half decent.

Idak

Also interested in Mapmyride calories that includes heart rate. Fitbit is saying about 800 cal an hour, the same as I get with a brisk walk, Mapmyride says 1500 and hours moving my 280lb body over rolling hill country roads at 15 mph.

zacster

Those numbers sound high, although my estimate is for a 170 lb person. RidewithGPS based on HR is always higher than the Wahoo Element/power meter readings but only about 10%. I figure this is all just an approximation anyway and I'm doing good with about 5000 kCal/week.

Idak

Thanks Zacster, that makes lots of sense.

DrIsotope

The non-sensors-no-PM-ballparker-guess-o-tron: 30kcal per mile. Speed is irrelevant. This errs to the side of caution. Climbing hills constantly will burn more, but going down them burns next to nothing.

OBoile

I wouldn't put too much faith in it. Without an actual power meter, Strava has no idea about the following things:

Wind direction and speed (when I ride into the wind, I get a lower calorie estimate as it think's I'm just not pushing as hard)
Riding position
Clothes you're wearing
Whether you're drafting or not

I'm fairly certain Strava wildly underestimates my daily commute, but wildly overestimates my group rides. I have a power meter on my indoor trainer. Today, my commute in, which I would classify as moderate intensity, was 50 watts lower than my recovery periods between intervals (1 minute on, 1 minute off) that I did yesterday on the trainer. There's no way that's correct.

salad_goat

I find this to be the answer as well. However, I have noticed there is about a 200 calorie difference when paired with a HRM. I believe the combination of the two to be most accurate.