Trouble getting accurate calorie data

[miscon1618]

I have a Specialized Turbo Tero 5 with the Mastermind TCD. I have that paired to my Wahoo Roam which is paired with my Polar HRM. I getting ridiculously low calorie consumption reported when the Wahoo data is synced to Strava. i.e. 100 miles.... 46 calories. Strava says that when 3rd party apps supply power meter data, that data is used to calculate calories. Any suggestions?? I don't understand how the power meter data is derived in the TCD. Can someone explain what might be going on??

 

[Ben J]

Calorie counts will come from one of two sources:

If a heartrate monitor is available, it seems like most systems will prefer this. It will estimate based on time in different heartrate zones with a formula based on weight, age, gender, etc. If you have not filled out personal information in the app, it may be multiplying by a wildly incorrect weight. Or, if the heartrate monitor is paired but returning bad data, it might think your heartrate is sometimes "0".

Otherwise it will fall back to using the power meter. People like to say that method is much more accurate, but there is a huge fudge factor because your body is only about 25% efficient at turning Calories into pedaling power. So the power meter will measure watt-hours very accurately but then that gets multiplied by about 4 to produce a calorie estimate. In fact, since one Calorie is about 4kJ (kilojules, which are the same type of units as watt-hours) I think often the calorie estimate is just literal kJ (the "about 4x" cancelling out).

Personally I get a very consistent "Calorie burn" number for a given ride when measured in kJ, but when estimating by heartrate it can vary a lot depending on how hard I went.

Without a HR monitor or a power meter, things may fall back to estimating power required based on distance/speed/incline. These will be totally inaccurate if you're on an ebike because it will not account for how much of the work was done by the motor.

 

[miscon1618]

@Ben J I'm getting confused about what should be paired to what... In your first paragraph (If a heartrate monitor is available).. I do have a working HRM, but I'm not sure whether it should be paired with the TCD or the Wahoo. Does that make a difference? Should I even be pairing the Wahoo with the TCD?

 

[Ben J]

Unfortunately it depends. Mainly on what app or device you want to use during your ride, and what service you want to save your rides on. For example, you could pair the bike and the HRM to to the Wahoo, use the Wahoo during rides, and upload it wherever it can (probably Strava and other places). Or you could pair your HRM to your bike and record the ride with Specialized's app (which can upload to Specialized's own site and Strava as well). Or you could pair your HRM and your bike to the Strava app and record directly in that.

I don't have a Wahoo but I suspect that you'd want to pair everything you can to that and record with that if you prefer the Wahoo. I use my phone and the setup varies depending on what I'm trying to do. On my Tero X I'll usually record with the specialized app no matter what (with HRM paired to the bike and relaying to the phone) but sometimes I ride with ridewithgps for directions. On my new Grizl:ON I've been riding with ridewithgps almost exclusively (because it works with the Garmin Varia radar) but the Bosch system records in the background automatically. If I pair the HRM with the Bosch setup I get it in the recording uploaded to Strava. But I can't see it while riding. If I pair it to ridewithgps, it's in that recording but not the other one.

 

[miscon1618]

@Ben J Thanks for the input. I double checked what I had paired with the TDC and the HRM I had was not paired with the POLAR HRM (although it was paired with the Wahoo). I completed/re-paired the HRM and Wahoo pairing to the TDC, then went on little test ride. Interestingly, the Wahoo did show zero calories after .82 miles. However, I ended the ride, checked the wahoo history and it showed 16Kj and 18 Calories. So I'm getting closer.

 

[Stefan Mikes]

@miscon1618:
Not sure what you are doing wrong.

I ride:

• A Specialized Turbo Vado 6.0
• A Specialized Turbo Vado SL

I use a Wahoo Roam 2 paired with either e-bike. Although I owned a Polar wrist HRM (and it worked perfectly), I stopped using it because my medication control my HR (cap it).

Here are two metrics I'm getting from e-bike -> Wahoo -> Strava:

I was using a solid electric assistance for both rides, so the kcal figures make sense.

 

[mschwett]

I have a Specialized Turbo Tero 5 with the Mastermind TCD. I have that paired to my Wahoo Roam which is paired with my Polar HRM. I getting ridiculously low calorie consumption reported when the Wahoo data is synced to Strava. i.e. 100 miles.... 46 calories. Strava says that when 3rd party apps supply power meter data, that data is used to calculate calories. Any suggestions?? I don't understand how the power meter data is derived in the TCD. Can someone explain what might be going on??

what does the power data say? using an average watts multiplied by time multiplied by approx 4 (the efficiency factor of the human body when cycling) is a very reliable estimate of calories burned - far, far more reliable than heart rate.

one possibility is that the roam isn't getting your power data. are you pushing data to strava from the garmin, or from mission control? take a look in strava and see if it's estimated power, or actual power.

a strava summary from a data file with power looks like this :

the calories is very simply the result of the time and average power. it does not matter how fast your heart beat, really, what matters is the amount of work you did in turning the pedals.

a summary which doesn't have power, like this one, estimates the calories from heart rate and speed. you can see in this case that although the ride was the same length, and a couple mph slower, and the average heart rate around 20% slower, the calorie estimate is way less than half which is simply not correct. no power meter on that ride.

 

[Jeremy McCreary]

Curious, do riders track calories burned to regulate their diets, to estimate how much nutrition to bring on similar rides, or for other reasons?

The new Specialized app shows me calories burned. It has my weight and rider power record for the ride but no heart rate data. Have to say, I'm pretty skeptical. Is there a reliable way to check these estimates?

If reasonably accurate, I guess I could use calories burned to know when I've earned an ice cream cone on the next ride.
;^}

 

[fooferdoggie]

I do it mostly to keep track of my effort. because its just faster then looking at heart rate and power. but I also need to know how many extra calories I need to eat after a ride.

 

[mschwett]

Curious, do riders track calories burned to regulate their diets, to estimate how much nutrition to bring on similar rides, or for other reasons?

The new Specialized app shows me calories burned. It has my weight and rider power record for the ride but no heart rate data. Have to say, I'm pretty skeptical. Is there a reliable way to check these estimates?

If reasonably accurate, I guess I could use calories burned to know when I've earned an ice cream cone on the next ride.
;^}

it’s very accurate - lots and lots of studies show that the efficiency of human bodies in turning food energy into mechanical power on a bike sits in a narrow range. heart rate is not really relevant, it’s only used as a proxy for effort when power data is not available. the work you’re doing is the pushing on the cranks, and the power meter measures that.

as noted elsewhere, the power “meter” built into the specialized e-bikes is not super accurate, but the amount it’s off by won’t change your ice cream earnings

 

[miscon1618]

what does the power data say? using an average watts multiplied by time multiplied by approx 4 (the efficiency factor of the human body when cycling) is a very reliable estimate of calories burned - far, far more reliable than heart rate.

one possibility is that the roam isn't getting your power data. are you pushing data to strava from the garmin, or from mission control? take a look in strava and see if it's estimated power, or actual power.

a strava summary from a data file with power looks like this :

View attachment 182942

the calories is very simply the result of the time and average power. it does not matter how fast your heart beat, really, what matters is the amount of work you did in turning the pedals.

a summary which doesn't have power, like this one, estimates the calories from heart rate and speed. you can see in this case that although the ride was the same length, and a couple mph slower, and the average heart rate around 20% slower, the calorie estimate is way less than half which is simply not correct. no power meter on that ride.

View attachment 182943

I really appreciate the insight you provide. I took a look at my Strava data and here is what it shows:

Based on 47w x 7.6hr x 4 = The calories should be near 1429. I'm still baffled about what 42 shows up.
Here is the data from the ride the next day.... no equipment change.

Again.... 49w x 2.2hr x 4 = results in 431 Calories. Very close to the 434 reported in Strava.

I don't know if we will resolve this, but I am learning more!

 

[mschwett]

definitely something awry with the 7+ hour one. in the second one the moving time is 2.25 hours, so 2.25 x 49 x 4 is pretty close to 434. average power is averaged over moving time, not elapsed time.

the fact that the work (kilojoules) is correct in the first one but the calories are not is really odd, some sort of strava bug. a kilojoule is .239 kilocalories, so when you add the 4x factor for the body efficiency the two numbers (work and calories burned) are close to the same. your first ride burned around 1500 calories.

incidentally, if the HR data is accurate, you were pushing too hard or too long on that long ride. the relationship of power to heart rate remains fairly fixed for a given level of fitness until you really get fatigued, dehydrated, etc at which point heart rate starts going up without your legs producing much more power. 96 miles is a big ride, even on an eBike.

 

[miscon1618]

definitely something awry with the 7+ hour one. in the second one the moving time is 2.25 hours, so 2.25 x 49 x 4 is pretty close to 434. average power is averaged over moving time, not elapsed time.

the fact that the work (kilojoules) is correct in the first one but the calories are not is really odd, some sort of strava bug. a kilojoule is .239 kilocalories, so when you add the 4x factor for the body efficiency the two numbers (work and calories burned) are close to the same. your first ride burned around 1500 calories.

incidentally, if the HR data is accurate, you were pushing too hard or too long on that long ride. the relationship of power to heart rate remains fairly fixed for a given level of fitness until you really get fatigued, dehydrated, etc at which point heart rate starts going up without your legs producing much more power. 96 miles is a big ride, even on an eBike.

Thank you again... wonderful info. I'm 72 years old and I knew this 96 mile ride would be tough! With what you explained, now I want to go back to Strava and look deeper into some of the analysis graphs. I bet it clearly shows what you shared...

 

[mschwett]

Thank you again... wonderful info. I'm 72 years old and I knew this 96 mile ride would be tough! With what you explained, now I want to go back to Strava and look deeper into some of the analysis graphs. I bet it clearly shows what you shared...

amazing! i can only hope to be doing such rides at 72.

 

[BlackHand]

Strava just passes along the Calorie number that was sent to it. But not sure if it was Wahoo or even the Mastermind that made the erroneous calculation.

Strava shows Calories as they were provided to us by upload partners. If no value is sent, or you record with the Strava mobile app, we use our own calculations.
source link

 

[Allan47.7339]

A brief article in Runners World has a few more insights:

How Accurate Is Your Wearable’s Calorie Count?

And is it a good idea to rely on smartwatch data for your energy expenditure?

www.runnersworld.com

 

[Stefan Mikes]

@miscon1618: Could you disconnect the Polar from the system and just do a longer test ride? Upon finishing the ride, sync Wahoo with Strava and check the calories. Then, connect Polar to Waho (or to Mastermind but not to both at the same time!) and go for another ride.

I am surprised to hear you are getting wrong calorie figure on one day then the proper data on another...