Originally Posted by
bruce19
I've also done some good rides where I burned 2-3,000 cals.
Note that on-line and heart-rate monitor estimates can be off by a factor of 2 or more.
2000 Calories is a 3 hour 60 mile/100km ride on flat ground, or a more moderate effort that distance with climbing.
3000 is generally a 100 mile ride.
If I wasn't measuring energy output with a power meter I wouldn't assume more than 25 Calories/mile in flat terrain or 35 in mountains.
I measured 3600 on my last long ride in the mountains, covering 104 miles and 10,000 feet
1 Watt = 1 joule/second, so 100W for 1 hour = 360,000 joules or 360kj. 1 Calorie = 4.2kj although cycling metabolic efficiency is never better than 25% so you can approximate 4 Calories in = 4.2kj out and round to 1 Calorie in = 1 kj out.
On "flat" terrain out-and-back using a power meter with +/-2.5% accuracy I measure about 100W averaging 15 MPH for 360 Calories / hour and 24 / mile; 150W at 17 MPH for 540 Calories / hour and 32 / mile; and 200W at 20 MPH for 720 Calories / hour and 36 / mile.
Weight adds some, but not as much as you'd expect.
50 pounds is about 23 kg.
1 mile is 1609 meters
23 kg * 9.8 meters/second^2 earth gravity * 1609 meters * .004 Coefficient of Rolling Resistance (unitless) = 1450.7 kg m^2/s^2 = 1450.7 joules = 1.4507 kj = 1.45 dietary Calories/mile on flat ground.
It adds more in the mountains, but still not much.
2000 vertical feet of climbing are 609 meters.
23 kg * 9.8 m/s^2 * 609 m = 137.2 Calories total
The result? I've gained 2.5 lbs.
After long ride you can have a few pounds of water in your swelling.
Eating saltier food can add a few pounds too.
Dehydration takes you the other direction - I drop about 3% of my weight when doctors tell me to pass on solid food for a day, empty my bowels, and drink nothing after midnight.
If you're monitoring size changes you need to weigh yourself daily at the same time and watch the trends.