Doggus

My wife is into this website called myfooddiary.com Anyhow, I rarely pay any attention to the stuff she rattles off that the site tells her after inputting her daily food/exercise, however - on Saturday it said I burned around 3400 calories. We did a tandem ride of 60 miles at an avg of 17.5. Does this sound right? I can't believe the calorie usage is that high. How can your body survive losing that many calories in 4 hours? I've looked at a couple other online calorie counters and they seem to concur.

BTW...if you have any suggestions as to a better piece of software or an alternative that will save me the monthly subscription to that website...I'd appreciate it.

LowCel 

The best thing you could do would to get an idea of calories burned would be to buy a heart rate monitor with calorie function on it. It won't be perfect but it will be closer. There really is no way of knowing how many calories you burnt by just putting in distance and average speed. There are too many variables.

For instance, yesterday I did a 52 mile ride with approximately 3,000 feet of climbing. Average speed around 17 mph. It took approximately 3 hours. According to my Polar S725 I burned close to 2,000 calories. Oh, I weigh 175 pounds.

A great free website is Fit Day. That site helped me lose 50 pounds last year.

* I used to have a couple of cheaper heart rate monitors before I bought the Polar. I had a Sigma Sport and a Phase. They both showed unrealistic calorie counts almost double what the Polar shows.

bmike

My 48 mile ride with 3800 feet of hills showed 4200 calories burned, from my HRM. I was out forever - 3 1/2+ hours, and it was 32 degrees. (This ride is usually a sub 3 hour ride!) My HR was in the upper aerobic for most of the ride, and near LT on some of the climbs. (I don't think the HRM takes temp into account for calories burned)

That said, I use CycliStats to record my rides, and the calories calc in the software is usually 1/2 of that from my HRM. Not sure which to trust. I don't really "count" calories, but I am curious as to how much I burned, just to know how hard I worked.

I weigh 185... and am continuing to drop... (shooting for 165 - 170)

Squint

First of all, most calorie estimators are way off. Secondly, riding a tandem usually requires less power for speed so if you're estimating calories from speed and mass, it's not going to work very well.

The best way to find out calorie expenditure on a tandem would be to have two separate powermeters and I'm not sure that would even work...

Doggus

Less power for speed for the weaker rider. I bring my wifes avg up, she brings mine down. I could avg that ride at 19+ on my own. Not sure where all this tandem folklore is coming from, I haven't seen it in real life. In our tandem club they're all slow. The singles leave us all in the dust. There's only one tandem team here that is fast and they ride a Calfee carbon fiber tandem...they can avg 21. Our best is 18. My worst on a single is 19. I sure hope our tandem gets faster..maybe the brakes are dragging

patentcad

Maybe you burned 3400 calories. Maybe you burned 2500 calories. Maybe you burned 4200 calories.

Doesn't matter. And you can't really measure this. Varies with age, metabolism, etc. I estimate that I burn about 50 calories per mile ridden - and that's probably on the high side since I'm older with a slower metabolism now (48 yrs old). So for me a 60 mile ride might theoretically burn 3000 calories. But this can't be right. Because @ 50 calories per mile I'd weigh 120lbs by now (I'm 170 or so and go down to 160 in the summer).

So forget about it. And yes your body can burn thousands of calories and survive. Besides what you eat, that's what those fat stores are for. And that's how you make them smaller.

terrymorse 

3400 calories in 4 hours = 850 kcal/hour

Seems a bit high. Actually quite high for a 4-hour ride.

850 kcal/hr corresponds roughly to 236 watts, which is very high. No way could I maintain 236 watts for 4 hours. Pros can on a tough stage, but not we mere mortals.

A more realistic figure for a 4-hour ride would be 150 watts, or 540 kcal/hr.

CdCf

Unless you're huge (think largest pro wrestler), you won't come close to burning off that much over 60 miles. I've estimated just over 30 kcal/mile for myself. Double that is highly unlikely, as I ride a heavy (37 lbs) bike, and I'm not very aerodynamic, at least not compared to average people on racing-style road bikes.

I assume you didn't climb a whole lot during the ride, by the way. If you did, that is a major factor and can raise energy expenditure massively, for a given speed, but at your average, I doubt very much climbing was involved.

So, let's say you're higher up than me, at 40 kcal/mile, that's still "only" about 2500 kcal for the ride. And even that is quite high.

BryanW

Hi, I use a table in Richard Raforth's "Bicycling Fuel". Though it was published in 1988, I have a gut feel that it's pretty close, because if it wasn't, I'd be losing a lot more weight than I do.

According to his table, a 60 mile ride at 19mph (which is what you would have done on your own, so assume the same effort level) burns off 2052 calories.

His table assumes the ride is flat, with no wind, (and also a "25% efficiency of the human 'machine'," whatever that means) so the actual amount would be higher, but I doubt anywhere near 3400.

velocity

It really depends where the calories are coming from then no one is a like in this area. Anything that takes in measure of weight and or age and factors it in is trying to cloan you. You would have to take a blood test to know what you burn at certain intensities. But I can tell you this- if you push your effort/intensity you will burn more calories from glycogen and fatty acids. Plus pushing your intensity will work the overload principle and you will get a training effect and a good caloric burn better than just staying at a moderate pace. Down side is you will not last as long and that you run a greater risk of injury.

Velocity

metal_cowboy

Keep in mind that body type, size and your overall conditioning will determine your caloric output. I am 6'4" and 289 lbs and burned 2600 calories yesterday on a semi-flat 30 mile ride with a 13.5 mph average. I am sure if a 5'6" 142lb speedster did this ride they may only burn 1200 calories and do it an hour faster.

Different strokes for different folks.

spunky

I like to use this software: https://www.kreuzotter.de/english/espeed.htm
I like the fact that it tries to take in other variables to achieve accuracy.

slvoid

Hmm according to this:
5' 10"
138 lbs
23lb total bike weight
Flat road
5mph wind
100rpm

300 watts
21.8mph, 165 miles
7:34
7800 calories

That's like, 3 big macs...

croshaven

I think 3,400 is way too high for 60 miles. Cut it in half, i.e. 1,600 and you'll be close. Even that may be high.

spunky

Not quite sure how you generated this because height above sea level and air temp make a difference. Also I think that it assumes you aren't drafting. Were you going into the wind or against it? Cruising at nearly 22 mph for 165 miles into a 5 mph headwind is pretty impressive in my book.

supcom

3400 sounds reasonable for a regular bike. Burning 750 calories per hour is fairly typical. 850 is a bit high, but not out of the ordinary.

As far as the body surviving a 3400 calorie burn, it's no big deal. One pound of fat contains 3600 calories. Your body stores about 2000 calories of glycogen in the muscles. Food eaten supplies additional glucose that can be used by the muscles. You can burn much, much more than 3400 calories in one event.

bmike

UMCA info on nutrition and caloric needs.

Chart showing calories burned at a given speed per KG of body weight, and other good information.

slvoid

Half the time I was leading, the other half I let someone get ahead and stayed to the side, maybe drafted about 25% of the time. It was a pretty flat ride with light winds, around 200ft above sea level and 70 degree temps. I was also in my drops, unless I was drafting, then I'd get less aero. I'd say the wind was blowing side to side at around 5mph give or take.
Being in the drops helps a lot.

spunky

Ahhhhhh.......so then 7800 calories might not be totally accurate if 25% of the time you drafted and the winds were actually crosswinds. Yeah riding in the drops does make a difference. Whenever I use this calculator, I tend to error on the side of conservatism. Still.....that's a nice bit of riding on your part.

berts

Please correct me if i am wrong. I found that:
1 watt = 0.86042065 kilocalories / hr

or

1 kcal/hr = 1/.8604 = 1.16 watts

thus

850 kcal/hr = (1.16 * 850) watts
or about 986 watts

please correct me if I am wrong

pacemaker

3400 kcals in 4hrs? With an average speed of 17mph that would be 14 kcals/min, which seems reasonable. My avg speed is ~17 mph which converts to ~16 kcals/min (Ht 69", Wt 160#, Age 40)I use a Polar HRM and they are accurate as long as the info you put into them is accurate. Some here have said there is no way to calculate kcals accurately. I tested my HRM against direct calorimetry by cycling on an ergometer at the same avg HR as a usual ride and the kcals burned was within 98% of my predicted kcals from my HRM; pretty accurate if you ask me.

pacemaker

Correction: Indirect calorimetry.

supcom

I believe you have neglected to take into account the inefficiency of the human body. The formula you used is simply a units conversion. For cycling, we are concerned about the number of calories burned by the body required to generate a given amount of output wattage. The 850 calories/hr includes the waste heat generated by the body when doing work.

cyclezen

Terry's numbers coincide with a lot of similar stuff I've read on the net. Also re-iterated in this good BF thread from Training-Nutrition .
also agree with Terry on the ballpark numbers he notes as 'reasonable'.
the 3500 Kcal definitely seems way too high.
I plugged some of my ride numbers into the 'calculator' that Spunky lists above and the numbers returned seem to jive to about 5-10% variance with what my HRM gives for Kcal. I'll use that calculator to check my HRM readings and also use those numbers for the rides on which I don;t wear the HRM.

As for Tandem riding - I've only done a small amount and its been a while since the last time, but as I remember riding on flats was always MUCH easier at any pace than riding single, unless the stoker wasn't pedaling at all. Uphill and climbing seemed about the same as riding as a single.The tandem forum prolly has bandied this around ad-infinitum...

Tex101

Has anyone toyed with the calculator here? It seems a bit high when compared to the UMCA chart.

https://www.bicycling.com/training/0,3317,s1,00.html