deepakvrao

Did a bit of search but could not get anything conclusive.

Earlier I used the Garmin Training Centre software, and a Garmin 500, and it would show that I would burn 450-500 calories per hour for a by and large zone 2 ride.

Now I'm using a Garmin 520, and reading straight from the Garmin. It shows 630 calories for first hour and about 530 for subsequent hours.

So, one, why so much difference between the first and following hours? And two, why more than the earlier readings? What do you guys burn for a 1 hour ride. I know the whole thing is not entirely accurate, but I'm on a weight loss thingie, so I enter this in myfitnesspal.com

For added info, terrain is mildly rolling, so each hour has about 100 meters of climbing, my weight is 165 pounds and height is 5'8".

rm -rf

Riders with power meters can get a more accurate calorie estimate, based on the energy they are actually producing.

Based on power meter rides, it appears that most riders use about 25-30 calories per mile. That's about 15 to 20 calories per km. The bike computer and online map estimates are often too high. A big hill climb or a very fast ride will use more, of course.

Zone 2, riding at a fairly easy pace, not breathing hard: About 15 mph or 24 kph. That's 15*25=375 to 15*30=450 calories per hour. So your Garmin is reasonably close, but maybe a little too high. It's always going to be an estimate, anyway. Plus or minus 20% of the actual calories would be very good.


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Some previous threads about riding and calorie estimates if you want more reading:

Calories consumed during 80 mile ride

Does Cycling Really Burn Up THAT many calories

deepakvrao

Thanks. Well, looked up the data again and I see that I spent a fair amount of time in zone 3 and a bit in zone 4 too, so maybe the 500 should be OK. Just curious as to why the first hour is always higher.

Just sold my PT hub :-(

BTW the total calories for the ride comes in at almost exactly 20 cal/km.

Drew Eckhardt 

1 Calorie = 4.2kj although cycling metabolic efficiency is never better than 25% so you can approximate 4 Calories in = 4.2kj out and round to 1 Calorie in = 1 kj out. I measure about 100W averaging 15 MPH which is 360 Calories / hour or 24 / mile; 150W at 17 MPH for 540 / hour or 32 / mile; and 200W at 20 MPH for 720 / hour or 36 / mile.

Depending on fitness Z2 can end somewhere between 130 and 160W for me although my aerobic threshold can be lower without enough base miles and that's the relevant number so a Z2 ride is probably 360-540. Power limits at all exertion levels are a function of size (Joel Friel says the riders he trains can get to 4.4W/kg at FTP +/- 10%, -0.5% per year past 35, and -10% for being female) and I'm not too big - 5'9.5" / 135-140 pounds in good shape. Larger riders (when lean - an extra 40-70 pounds didn't make me better) can break 200W and 720/hour.

The power numbers are higher than I get with on-line calculators or glancing at instantaneous power output because maintaining those average speeds means riding faster to compensate for slow sections where the power to overcome aerodynamic drag increases with the cube of velocity.


350 - 750 Calories measured with power.

Only eat enough to sate your hunger (you need to replenish your glycogen stores to avoid catabolizing muscle) half an hour after the last bite and you should do fine without trying to figure out calories in and calories out.

100 meters of climbing * 85kg for you and bike * 9.8m/s^2 = 83.3 kj / Calories plus whatever you'd expend for that speed on flat ground.

gregf83 

I weigh about 165 and a typical endurance ride for me would be around 700 Cals/hr. I'm not sure there's a standard definition of Z2 but I use 55 to 75% of FTP (from Golden Cheetah). I would normally ride towards the higher end of that range. I commute and most rides average around 1:05 and 725kJ with about 50% spent in Z2.

f4rrest

800/hr, z2 is around 230 watts and 120 bpm, on average. I'm 180-185.

chaadster

Man, I want that kind of capacity! 230w is low L3 power for me, even though I weigh 220lb. And at 120bpm...damn! What's that, like 330w FTP and 190bpm LTHR?!? I'd be killin' it with that. Kudos!

f4rrest

Thanks chaadster. Unfortunately, I max out at 180 bpm. Haven't tested FTP in months, since it makes my back sore, but the CP curve estimate is pretty generous. If only I didn't have all these nagging injuries!

Machka 

I go with 100 cal for every 5 km.

If I ride fast, I burn more per hour. If I ride slow, I burn less per hour.

surgeonstone

Always ignore calorie burned estimates, they serve no purpose other than to make you fatter. It is a proven point.

silversx80

My Z2 power caps out at around 215W, based on an FTP test about 4 weeks ago. My HR Z2 caps out at 152 bpm, according to my max of 195. The problem with that is my Z2 HR puts me around 250-260 Watts. 215 W is about 130-140 bpm, and 775 kJ/hr.

chaadster

That sounds normal to me. My top end L2 power is 225w, and Z2 HR is 110-145bpm (I use "level" for power, and "zone" for heart rate to avoid confusion), and yeah, Z2 HR can take me right into L3 power range even warmed up after 20 mins or so, but if I go hard for awhile, my HR will drift up, and say after an hour, L2 and Z2 are pretty much aligned.

valygrl

Best way to find out what *you* burn per hour is to go back and look at your power data before you sold your powertap. KJ = calories, pretty much. Find some rides about the same length & effort as what you are doing now (at a time when you were similar weight) and check what your KJ/hour was on those.

What you burn per hour is highly dependent on your wattage so looking at someone else's info is going to be less accurate than looking at your own.