Fitness trackers / Smart Watch calories
Discussion
Evening folks
Being a late comer to modern tech, I recently bought an Apple Watch 9 to monitor my movements. Doctors orders as I was recently diagnosed with hypertension.
I've been using Cycle meter for years as it's simple, cheap and just works. So with the watch, I enabled Cycle Meter's calculate calories from heart rate and elevation.
The odd thing is if I do a 12 mile thrash on my bike, Cycle Meter measures 900 calories burned, whereas if I do a cycle workout with Apple activity, it measures 600 calories. Its pretty hilly where I live and my heart rate often gets up to 180, but which one of the two do believe?
500-600 seems more realistic to me for such a short ride. I know you can use wattage as well but I don't have that kit for my bike.
Any pointers from seasoned cyclists?
I'm 6ft and 82Kg if that makes any difference. Average speed on the road keeping up a hard cadence is 18mph. The bike is a Giant Anthem 29er with mahoosive tyres, which might account for the heart rate
Not ideal for road use but I haven't got around to buying a road bike yet.
Being a late comer to modern tech, I recently bought an Apple Watch 9 to monitor my movements. Doctors orders as I was recently diagnosed with hypertension.
I've been using Cycle meter for years as it's simple, cheap and just works. So with the watch, I enabled Cycle Meter's calculate calories from heart rate and elevation.
The odd thing is if I do a 12 mile thrash on my bike, Cycle Meter measures 900 calories burned, whereas if I do a cycle workout with Apple activity, it measures 600 calories. Its pretty hilly where I live and my heart rate often gets up to 180, but which one of the two do believe?
500-600 seems more realistic to me for such a short ride. I know you can use wattage as well but I don't have that kit for my bike.
Any pointers from seasoned cyclists?
I'm 6ft and 82Kg if that makes any difference. Average speed on the road keeping up a hard cadence is 18mph. The bike is a Giant Anthem 29er with mahoosive tyres, which might account for the heart rate

So 12miles at avg of 18mph - so 40 minutes activity.
It’s probably nearer the lower number. You’d need to be averaging circa 250w-260w for an hour to be around 1000kcal burned. And at your weight, unless it’s exceptionally hilly, you’d be going quicker off that than 18mph avg I’d imagine. And of course you’re not riding for an hour either.
To burn 900kcal in 40 minutes you’d need to be around 300w, which on most UK terrain at your weight would be over 20mph avg
It’s probably nearer the lower number. You’d need to be averaging circa 250w-260w for an hour to be around 1000kcal burned. And at your weight, unless it’s exceptionally hilly, you’d be going quicker off that than 18mph avg I’d imagine. And of course you’re not riding for an hour either.
To burn 900kcal in 40 minutes you’d need to be around 300w, which on most UK terrain at your weight would be over 20mph avg
A wrist monitor for HR is not good on the bike, your major peaks may not be measured at all, so the calorie calculation will not be accurate.
I do regular sessions on a turbo trainer and wear a wahoo HRM on a chest strap. The software tracks power, cadence and HR.
I also wear a fitbit wrist monitor. Which tracks heart rate , breathing and other stuff.
The fitbit on the wrist is rubbish at monitoring HR during cycling it just doesn't work properly. The chest strap is far more accurate.
The fitbit has become my tool to track resting HR as a comparison across several days, sleep hours, and it does some sort of calc to track heart fitness.
These seem to work well when the figures are taken as a trend rather than an absolute measurement.
The figures off the turbo trainer using the HR strap are useful to show the actual efforts and track power and speed over time. I also use the HR to measure effort, basically to make sure I'm not over doing it. (I'm 77 so I can't just run into the red without planning!)
I do regular sessions on a turbo trainer and wear a wahoo HRM on a chest strap. The software tracks power, cadence and HR.
I also wear a fitbit wrist monitor. Which tracks heart rate , breathing and other stuff.
The fitbit on the wrist is rubbish at monitoring HR during cycling it just doesn't work properly. The chest strap is far more accurate.
The fitbit has become my tool to track resting HR as a comparison across several days, sleep hours, and it does some sort of calc to track heart fitness.
These seem to work well when the figures are taken as a trend rather than an absolute measurement.
The figures off the turbo trainer using the HR strap are useful to show the actual efforts and track power and speed over time. I also use the HR to measure effort, basically to make sure I'm not over doing it. (I'm 77 so I can't just run into the red without planning!)
wrt to wrist vs chest based heart rate, it definitely depends on the device. Some of the wrist based ones are rubbish, but I've just got a Garmin Forerunner 255 and have done sessions with a chest strap paired to my wahoo bike computer and the ride being recorded separately on the watch and the heart rate tracks pretty much perfectly between the two.
Cheers guys. I know smart watches aren't the last word in accuracy, I was just after a rough estimate 
After speaking to a couple of local mega cyclists who have all the gear, and some idea, they average 650 calories per hour at their speeds. So the watch isn't a million miles off. That'll do me
I will stop using Cyclemeter then and just Apple's cycle workout as it's a lot closer to reality
Went out for a 70 minute road ride today and CM recorded 1100 calories, and the watch recorded 700.
I need to get a road bike I think. The mountain bike is doing my back in on road rides.
Oh, my 12 mile ride takes 50 mins, so I'm a bit off the 18mph average, again that was going off Cycle meter.

After speaking to a couple of local mega cyclists who have all the gear, and some idea, they average 650 calories per hour at their speeds. So the watch isn't a million miles off. That'll do me

I will stop using Cyclemeter then and just Apple's cycle workout as it's a lot closer to reality

Went out for a 70 minute road ride today and CM recorded 1100 calories, and the watch recorded 700.
I need to get a road bike I think. The mountain bike is doing my back in on road rides.
Oh, my 12 mile ride takes 50 mins, so I'm a bit off the 18mph average, again that was going off Cycle meter.
lufbramatt said:
wrt to wrist vs chest based heart rate, it definitely depends on the device. Some of the wrist based ones are rubbish, but I've just got a Garmin Forerunner 255 and have done sessions with a chest strap paired to my wahoo bike computer and the ride being recorded separately on the watch and the heart rate tracks pretty much perfectly between the two.
DC Rainmaker review on Apple Watch 9 says thats pretty accurate as wellhttps://www.dcrainmaker.com/2023/09/apple-watch-se...
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