Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.proRow
03-02-07, 07:05 PM
I hate using a trainer and I hate using a stationary bike even more, but due to some nasty snowfall and other complications, I've been forced wrack my knees on the stationary bikes indoors. Anyway, I average 18 mph for an hour on medium to high resistance around 180-220 Watts, but at the end, this thing tells me I've burned 1,200-1,400 calories. This can't be right, I would guess around half of that maybe.
My simple physics tells me: energy = power x time = (200 J/s)*(1 hr)*(3600 s/hr)*(0.000239 kcal/J)
= 172 kcal (of mechanical work required)
And factoring in my body's efficiency, the amount of mechanical work produced per energy used (because much heat is produced, etc.) roughly equal to 0.25, (172 kcal)/(0.25) = 688 kcal,
which is almost exactly half of what the display tells me.
So I would think not to trust these numbers, but does anyone here know if there is a way to find out how the machines come up with these figures? Or do you know of a more reliable way to track the amount of energy exhausted during a ride? I don't really care how many calories I burn. My simple training program of ride hard and if you're hungry, eat; thirsty, drink, etc. has worked since high school. I just get the idea that a lot people are probably getting of these bikes thinking they just burned 1000 calories, go eat a ton, and actually end up putting on a bunch of fat because of too much reliance on these calorie counters.
My simple physics tells me: energy = power x time = (200 J/s)*(1 hr)*(3600 s/hr)*(0.000239 kcal/J)
= 172 kcal (of mechanical work required)
And factoring in my body's efficiency, the amount of mechanical work produced per energy used (because much heat is produced, etc.) roughly equal to 0.25, (172 kcal)/(0.25) = 688 kcal,
which is almost exactly half of what the display tells me.
So I would think not to trust these numbers, but does anyone here know if there is a way to find out how the machines come up with these figures? Or do you know of a more reliable way to track the amount of energy exhausted during a ride? I don't really care how many calories I burn. My simple training program of ride hard and if you're hungry, eat; thirsty, drink, etc. has worked since high school. I just get the idea that a lot people are probably getting of these bikes thinking they just burned 1000 calories, go eat a ton, and actually end up putting on a bunch of fat because of too much reliance on these calorie counters.