This is a SWAG for calories burned cycling 12-15mph:
- Divide your feet climbed by 10.
- Divide again by your average MPH.
- Add that to your total miles.
- Multiply the new number by the weight in pounds of you, your bike, and everything you’re carrying.
- Multiply the new number by 0.105 (or divide by 9.5).
- (Use 0.115 or 8.7 if you only know your own naked wake-up weight.)
- That is pretty close to your calories burned for the ride.
- Baseline here is me, 6’5″, anywhere between 250 and 290 pounds plus bike weight (any bike).
BMR is not a part of this SWAG:
- BMR is how much you burn in 24 hours of sleeping.
- Most people are around 9kcal per pound per day.
- BMR and is not based on your activity level (see TDEE).
- BMR is based in your microcellular efficiency, and is influenced by hormones.
- If you are on severe caloric restriction, it goes down.
- Thyroid issues can affect this either way.
- Baseline here is me, at 285 pounds, and averaging 2550 kcal per day.
Faster speeds pick up exponentially more wind resistance.
- Twice the airspeed has four times the wind drag.
- Higher density altitude has proportionally less drag.
- Shorter and narrower shouldered people people have less wind drag.
- Fatter people are slightly more aerodynamic, so the increased wind profile is not THAT much of an issue.
- Cycling 10mph into a 5mph headwind has as much wind drag as cycling 20mph with a 5mph tailwind.
- 12-16mph is the 50% transition for wind vs other factors on flat ground. (13mph for me at 6 sqft)
- Baseline here is me, with about 6 square feet of frontal area, about 22 Watts at 10mph, and about 150 Watts at 20mph, just for wind.
Rolling resistance is a big part of drag.
- Increases linearly with speed (2x speed is 2x the rolling drag).
- Lower weight is better (because tiny bumps have to push you UP over them).
- Race tires can be half the CRR of average tires.
- Wider tires are better by around 1% per mm with 23mm as baseline.
- Baseline is me, at 310 total, 31W at 10mph, or 61W at 20mph on 1% grade.
Routes with less uphill than downhill will cost fewer calories.
- Increases linearly with speed (2x speed is 2x the gravity drag).
- 1% uphill is 2x the drag of rolling resistance. 2% is 4x.
- Lower weight people do way better on both gravity and CRR.
- Baseline is me, at 310 total, 62W at 10mph vs 124W at 20mph on 1% grade.