gregf83 

Studies I recall are most cyclists fall in the 18-24% range and it’s not well correlated to fitness.

GhostRider62

[QUOTE=david101;22179326]What fight?

Being told you are wrong is not a fight.

When you put yourself into a hole, just stop digging.

I apologized for hurting your feelings and even offered that your shock could be due to generational differences. Next time, instead of snapping off with, "did you read my post"; perhaps, re-read your own especially when it goes against what others wrote, aside from some basic physics. Then, just let it go or write, "Oops, I wrote that poorly or that is not what I mean". Reaching for the shovel and doubling, tripling down usually doesn't work.

livedarklions

Yes, I think the 25% efficiency figure is used because it makes the math easier, not because it really reflects what's going on. It's actually quite a bit above average.

If I recall correctly, the only way to accurately measure calories burned involves capturing all of the exhaled breath of the subject during the activity. That could be done during a stationary bike ride, but not realistically under real road conditions.
I'm also suspicious of using average speed because I think you'd have to do some pretty tough calculating based on the actual speeds during the ride. Someone with better math skills than I would probably need to weigh in on it, but the cubing of air resistance means that the farther above mean the speed is, the greater the divergence from the mean energy requirement, correct? So, if the average speed is 17 mph, the higher speed values will have a bigger difference from calorie burn at mean speed than speeds below the mean. Thus the total calorie burn per minute curve should skew somewhat to the right of the speed curve (or something, my stats are several decades out of practice).

gregf83 

Turns out my memory wasn't correct, Differences in efficiency between trained and recreational cyclists found experienced cyclists were more efficient.

livedarklions

More importantly, though, those averages are significantly less than 25%, Only one guy even got close to that number.

What's the source?

burnthesheep

Recently on the lines of the speeds and power and such above.........I finally hit a silly goal I'd had for years. 20mph on a ride that gets 100ft per mile elevation, for an hour. The speed was on, I was short by a couple feet elevation. It "only" took me about 235w. The key was to have the skills to take corners at pace and constantly meter out the power evenly. No freewheeling unless totally unavoidable. Could have gone faster but lots of neighborhood curves and such. Meter might read low also, no idea. Seems low for curvy stuff and 1940ft in 20mi at 20mph.

livedarklions

That's a good day! Mazel tov, silly goals are fun.

gregf83 

The source is in my earlier post, just click on the name of the paper. The figures in the paper are for Gross Efficiency (GE) and are useful for comparing trained and untrained athletes. Using gross efficiencies will give you the total calories burned during an activity which will include calories from your Base Metabolic Rate (BMR). To determine the 'extra' calories associated only with exercise and not include BMR they normally would use a 'delta' efficiency number which is a little higher than GE. I think 25% is probably close enough given the variability seen between individuals.

pgjackson

Don't know if this video has already been posted, but it really makes things pretty easy to understand. Calories in, calories out.

pgjackson

ssedha

Thank you for sharing this! I'm also in the boat to lose about 20 lbs and this video was helpful!

RH Clark

I would agree to a large extent on the importance of calories, however just like everything else in life it isn't just black and white.

pgjackson

I didn't watch the entire 30 minutes, but nothing in the first 10 minutes refutes the idea that to lose weight your caloric intake must be less than your caloric expenditure. Can anyone cite examples of diets that recommend eating MORE calories and expended? Yes, what you eat matters...but weight loss is still about calorie reduction.

OBoile

The title of the video is misleading. The person in the video is arguing in support of calories in vs calories out. He's refuting someone who says hormones are what matter.

mschwett 

that's a great ride. one of the things i like about my "main" route is that i've done it so many times that the limitations are now more about true cardiac or muscle output as opposed to not knowing how fast a turn can be taken, what the conditions up ahead are, what the timing of a light is, etc. and it's super satisfying to ride for an hour and a half without freewheeling

235w suggests you're very aero and are turning all the energy used getting up the hill into productive motion going down rather than braking! i know that it would take me WAY more power than that to achieve the same result.... but of course i'd burn more calories lol.