PAPOO1986

Hey all

I just started commuting to work recently, I downloaded the strava biking app to track my ride and it says i bike 14miles each way to work at an avg speed of 14.5mph. took me 57 min to get to work today. I was looking at calorie calculators and they all claim im burning between 600-750 cal. im not sure if this is accurate. i weigh 205 please help

chasm54

Looks high, most calculators do seem to err on the high side when estimating calories burned. I'd suggest that 400 - 500 would be nearer the mark, more if there's a lot of wind or hills. If you estimate 25-30 kcal per mile you won't be massively wrong.

UberGeek

Sounds about right, assuming you have no metabolic diseases. 21 miles nets me about 1000 calories, and I'm not far off of your weight. I use Runkeeper, however, I assume both have similar formulae for calculating burn rate.

Now, I'm presuming it's accurate, because I also use MyFitnessPal to log meals. And, I am scheduled to lose 1.5 lbs per week. And, I am not far off the mark, average about 1.4 lbs per week in weight loss.

tjspiel

I've worn a heart rate monitor on my commute in the past and for what it's worth those numbers seem in the ballpark. I'm sure there's a lot of variability. I'd burn a lot more calories covering the same distance in the winter with studded tires and a little snow on the ground.

Before the heart rate monitor would calculate calories I had to determine and input a resting heart rate. Given that I'd assume that not everyone burns the same amount of calories doing the same thing. So if an accurate calorie count is important you probably can't rely on just those estimates that you've gotten.

chasm54

Don't assume accuracy. HR monitors use very different algorithms for this, and report widely differing results. If one has a powermeter one can make a reasonably accurate calculation, because it record how many kilojoules are produced and kilojoules divided by four is approximately Calories burned. Those who use powermeters consistently report Calorie consumptions lower than HR monitors alone, in my experience.

I weigh 195lbs. For me to burn 600 calories riding 14 miles on a flat, windless road I'd need to be riding at close to 22 mph.

UberGeek

And, your error is assuming flat, windless roads. Runkeeper is pretty accurate for myself (I obviously have very average metabolism), as I am losing weight right about on track as I'm supposed to be.

Runkeeper (And Strava) take into account incline and decline, as well as speeds at point in time, rather than average speed for their burn calcs. Runkeeper also uses NOAA data to estimate headwind/tailwind conditions (Strava might, I don't know).

Power meters are about as accurate as it gets (I think), shy of that breathing harness athletes wear to measure calorie burn rate. However, I've found RK (And Strava) to be close enough for the "Everyman" usage (Again, assuming a pretty normal metabolic rate).

chasm54

I changed my example to reflect more accurately the OP's trip.

I think you are overestimating Strava's sophistication. My powermeter-using friends all say that the power (and therefore calorie) data they get from Strava is markedly inaccurate compared with what the specialist software produces. Something to do with Strava failing to average the data points, or something.

UberGeek

Ah, I get you now. You're specifically saying Strava isn't as good as other products, not saying ALL products aren't good

I only used Strava a couple of times (Before settling on Runkeeper), so I guess I assumed too much. I figured since Strava was as highly rated as Runkeeper, they'd be on par.

PS To really get your power meter using friends, ask them when the last time their torque transducer was calibrated lol

rumrunn6

re: "14miles each way to work at an avg speed of 14.5mph. took me 57 min to get to work"

that's the perfect scenario if you ask me. enjoy!

baron von trail 

500-750 Kcal burned per hour cycling, depending on speed, is my understanding.

calyth

I suspect that the most accurate bike-ready accessory would be a power meter.

My bike computer has an altimeter and HR, and it reports higher KCal burnt than something like Endomondo (Strava doesn't make a BlackBerry 10 app...)

Take the actual value with a grain of salt, and if you really need to measure against something, use it as a relative metric - if it says you've burnt more Calories today than yesterday's within the same app, you probably did use more energy.

I wouldn't rely most of these things for actual Calorie counting.

ItsJustMe

I think trying to figure out how many calories a given activity is burning is a complete waste of time. Without a full medical work-up so that you can tune the numbers to your particular level of fitness and body numbers (vO2, metabolic efficiency, etc) I think it's just pretty much guesswork even with a power meter. Your pedaling technique could be wasting tons of power that never gets transferred to the drivetrain, so even a power meter might be vastly wrong.

PAPOO1986

Wow

Really great response thanks a million ppl ,Im gonna go and find a hr monitor. I was thinking it was like 350 cals but its nice to see those numbers. I assume it would be safe to say i burn about 1000 a day round trip, but then i also do weightlifting 4 days a week and on a 1700 calorie diet. may need to eat more so i dont lose muscle lol. I bike through prospect park and there are some hills. Id say 20 percent is hilly. thanks again guys.

PAPOO1986

according to strava it says there is a 500ft gain in elevation

calyth

Eat after ride, just like how you might eat after you lift.

AstroEng

The Clydes forum has a lot of post on this if you are still interested in more information. Posts comparing power meters, HRMs, stationary bikes, etc.

acidfast7

That depends on many factors including rolling and aerodynamic resistance. I burn more kcal when riding on a knobby-tired MTB on the street compared to a race/road bike.

mrleft2000

I've always found 35cals/mile on a hybrid and 30cals/mile on a road bike to be a good estimate. That's assuming I'm giving a decent effort. I think weight is less of factor for cycling as it is for something like running/walking because a larger portion of the energy expenditure is overcoming wind/rolling resistance as the bike rolls along which is less a function of one's weight.

UberGeek

Simple physics tell us moving a 1kg mass takes less energy to do then moving a 3kg mass; no matter the method of doing it

mrleft2000

Of course it takes less energy to move a 1kg mass versus a 3kg mass. That's not what I was saying. I was saying the difference factor to roll a 3 kg mass versus a 1 kg is less than the difference factor of hand-carrying a 3kg mass versus a 1kg mass. "Simple physics" tells us that maintaining rolling only has to overcome the losses of drag and rolling resistance. If not for them, the conservation of momentum would continue to move either mass indefinitely. When walking, the only major conservation of momentum effect in play is the pendulum effect of your arms and legs swinging.

For every step, you have brief moments of acceleration, ergo why you move with a gait instead of a constant velocity, thus energy spent walking your body any distance is a linear function of distance and mass. When rolling, on a flat ground, if not for drag and rolling resistance, you only have to provide the initial acceleration to get up to speed and with nothing else, you would eventually get to your destination irrelevant of how far away it is, ergo the energy for frictionless rolling is not a linear function of distance and mass. Energy spent overcoming drag and rolling resistance is a linear function of distance. Rolling resistance is function of mass but it's only one component of it. You have suspension losses as well, but this is "simple physics", so we've approximated that out.

If not for frictional losses, energy spent to move mass is needed for acceleration not velocity because of the conservation of momentum. This is why it takes less total energy to move a man+bike a mile than a man walking a mile.

acidfast7

UberGeek

And, you still have to expend the energy to get you to velocity, which is more for the 1kg mass, than the 3kg mass; which is the big player. And, since we're never talking about frictionless environments (Which only exist in math problems), the energy required to maintain velocity of a 1kg mass is less than a 3kg mass.

So, yes, it's less of a difference than when walking; but it's not like it's the same for a 100lb bloke and a 200lb bloke to ride a 10 mile ride.