6

I've just finished a long bicycle tour on a loaded touring bicycle, and I'm interested in calculating the number of calories I must have burnt over the trip. However, all the calorie calculators I come across don't take into account the weight of the bicycle, which means the data must be a significant underestimate.

So, what is the calculation used to calculate number of calories burned on a bicycle ride, and how can it be modified to take into account the weight of a heavily loaded touring bike?

  • 2
    The reason they don't ask bike weight is it makes no difference - weight is only significant on hills and acceleration, even then, its way less significant than the error in the guessed Calories burnt. Wind has far more impact - did you record wind speeds on the days you were riding. – mattnz Aug 25 '15 at 21:00
  • I think the question is "what is the formula for calculating calories burned" not "is there a way to get an estimate of how many calories I burned." Does anybody know how to do the actual math? – dlu Aug 25 '15 at 21:21
  • @mattnz that assumption only works for the common case where the rider weighs 5x of more what the bike does. When the bike weighs about the same as the rider and the frontal area is doubled or worse the whole "bike barely matters" assumption is not relevant. – Móż Aug 25 '15 at 21:58
  • 1
    The simplest approach is to add the "extra" weight on the bike to your claimed body weight. – Daniel R Hicks Aug 25 '15 at 23:18
  • You may be interested in the answers to bicycles.stackexchange.com/questions/30413 – mattnz Aug 26 '15 at 1:32
4

To be honest, you're really asking this question too late. If you had asked before your tour, I believe the easiest way you could have measured it would be to find a cycling app which takes your weight and your other physical information. Then you simply weigh your fully loaded bike and add that weight to your own, then the app would measure your total calories burned. (Even this would only be a rough estimate).

However, there is no solid answer to this question. As I said before, you would have been better off asking this prior to the trip, as there are dozens upon dozens of factors needed to give you an accurate BALLPARK of how many calories you've burned. (I.e. Speed, terrain, average gradient, food consumed while on your trip, average power output, length of time spent in the saddle, cadence, over all distance, e.t.c.)

I suppose if you wanted a very rough estimate, find a calorie calculator online, input the total weight, (you and the loaded bike), take the distance traveled, and the estimated total time in the saddle. This method would be fairly inaccurate, but without the factors listed above, I believe it's the closest you would get.

  • All of the ride data is on Strava, so I could easily change my weight data on there to get the results you're suggesting. I am actually asking what the calculation is though, not where I can get the result. – majackson Aug 25 '15 at 17:16
  • 2
    Perhaps you could add a new bike to Strava, and then assign that bike to the ride. I'm pretty sure assigning a different bike to the ride will cause it to recalculate the calories burned. – Kibbee Aug 25 '15 at 17:49
  • 1
    @Kibbee is actually correct. At least about being able to add different bikes to different rides. However, I experimented with it myself and the bike itself does not alter the calorie count at all. – Weirix Aug 25 '15 at 18:26
  • 5
    Actually it does affect the calorie count. I just tried it on my own account. I had a ride that was 1 hour 50 minutes, and covered 50 km. I did the ride on my touring bike which I have entered as 12 kg. Strava says I burned 965 Calories. When I switched it to the Tag Along Bike, which is just the same bike with the tag along mount for my kid mounted, which I have entered at 60 kg, it changes the calorie count to 1201 calories. You have to make sure you refresh the screen after changing the ride, but it's definitely taking the bike into account. – Kibbee Aug 25 '15 at 18:54
  • 2
    Also, it sometimes seems to take a little while to change the calorie count, even if you did refresh it. When switching my ride back to the original bike, the first refresh did not show the calorie count changed back to the original value. I had to refresh a second time. Also, depending on the weight difference of the two bikes, it may or may not end up calculating a different number of calories. My second bike was a full 48 kg more than the original bike. – Kibbee Aug 25 '15 at 18:58
2

You can't.

Calories burnt depends on your speed, elevation change, and your body composition. e.g. riding at 30mph burns more than double the calories per hour than 20mph.

The calorie calculators just make a rough approximation, and their margin of error is significantly greater than the difference between their assumed bike weight and yours.

Just take what they provide as an estimate, or supply your weight as being your actual weight plus the extra weight on your bike and call it good.

  • My whole trip is logged by my Garmin device, so I do actually have speed and elevation change data. – majackson Aug 25 '15 at 17:13
  • Tuesday morning I commuted 23 km to work into a fairly steady 60-70 kph head wind (gusting to 90 according to the weather report). Tuesday evening I commuted 23 km home with a 70-80 kph tail wind (gusting to 120 - and they tell us it is summer here...). Total elevation change less than 2 metres, I doubt that any calculation using my instantaneous velocity and elevation on those two trips could calculate calories burnt to within a factor of 2 without taking the wind into account. – Penguino Jan 24 '17 at 21:10
  • @Penguino: ok, your point? – whatsisname Jan 24 '17 at 21:34
  • My point is that mass, speed, and elevation alone won't be sufficient to approximate calories burned if other variables are not taken into account. Even minor head-, tail-, or side-wind will have an effect as might tire pressure, atmospheric pressure, mechanical condition of the bike, road surface (smooth tarmac, rough tarmac, cobbles etc.). Therefore the specific equation used by any particular calorie calculator (based on speed, distance, altitude, and rider mass alone) is probably irrelevant and any modification of such an equation to take bike weight into account is pointless. – Penguino Jan 25 '17 at 3:13
  • @Penguino: and is that not basically what I said when I opened with "You can't"? – whatsisname Jan 25 '17 at 3:15
1

I recently saw a site which gives a calculation, and shows formulas, which will take in to account the weight of the bike: http://www.tribology-abc.com/calculators/cycling.htm They combine the weight of the rider and the bike to get a total mass mtot and then this is multiplied by a rolling resistance coefficient Cr and acceleration of gravity g to get a rolling resistance force: Rolling resistance Frol = mtot g Cr. A separate calculation gives the air resistance force; These are added to get a total drag force, then multiplied by the speed to get the power required. You can change the rider weight, bike wt, drag coefficients, uphill slope, etc. A final calculation estimates the efficiency of the cyclist in converting food calories (kcal) to delivered pedal energy in kilo-joules (kJ). For example, using the default parameters, increasing the bike weight from 15 to 30 kg increased the calories from 577 to 589 kcal for a 60 min ride. Another site which also discusses this is http://www.cptips.com/formula.htm

  • Welcome to Bicycles @Mark29. +1 Nice first answer :-) – andy256 Jan 24 '17 at 21:17
0

If you're able to upload the ride to Garmin Connect, or Strava, you can get an estimate of calorie burn on the basis of speed, elevation, and so forth. If you were wearing a heart rate monitor, the estimate from Garmin will be much more accurate, but unfortunately at this time Strava does not factor heart rate into their calorie estimate.

0

I'm just going to ignore fancy apps, gps, and physics all together:

Figure out how many calories you consume on a typical/non-exercise day and multiply that by the days in your bike tour. Subtract that from the amount of calories you consumed during the tour, and that will be a pretty good estimate of how many calories the actual biking required.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.