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Calories and cycling

Old 08-10-21, 01:34 PM
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Originally Posted by livedarklions
So, yes, 15 minutes of 30 mph is going to require a LOT more energy than 15 minutes of 24 mph.
A LOT? Thanks. That's a very helpful answer. I'd though that it might be only a 'lot' or even a 'LITTLE'.
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Old 08-10-21, 01:41 PM
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Originally Posted by WhyFi
Have you ever tried to go fast on a bike? Drag becomes the dominant form of resistance somewhere in the range of 8-10mph. At 17mph or so, which is probably the cruising speed necessary for a 15mph average with stop-and-go, it'll account for 70%+. Do you think that it warrants inclusion, then, in our first approximation? Maybe?
I think that you'll find that you haven't answered (or even tried to answer) the question that I asked.
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Old 08-10-21, 01:51 PM
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Originally Posted by livedarklions
Is this the fourth or the fifth rewrite of the "spirit" of your OP?
I'm not sure to be honest. I only remember one version, but if you're kind enough to show me the others I will count them for you.
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Old 08-10-21, 02:02 PM
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Originally Posted by david101
I think that you'll find that you haven't answered (or even tried to answer) the question that I asked.
No, I haven't, because I'm not interested in doing so. I had more interest in addressing these two absurdities:

Originally Posted by david101
Elevation change and wind direction would also play into it, but not your speed of travel or any biological details.
Originally Posted by david101
It's a question of which terms we choose to neglect in our first approximation.
but I have pointed you in the direction of the tools to answer your own questions about energy expenditure differences at various speeds. Have fun.
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Old 08-10-21, 02:09 PM
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Originally Posted by WhyFi
I had more interest in addressing these two absurdities:
Taken out of context, the first statement is indeed incorrect, although perhaps not absurd.

If you believe that the second statement

It's a question of which terms we choose to neglect in our first approximation.
is 'absurd', then honestly I'm at a loss.
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Old 08-10-21, 02:44 PM
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Originally Posted by david101
Taken out of context, the first statement is indeed incorrect although perhaps not absurd.
fify

Originally Posted by david101
If you believe that the second statement is 'absurd', then honestly I'm at a loss.
If you're uncertain on whether or not to include the dominant form of resistance, the majority of time, for just about any cyclist over 9 years old, then I'm at a loss.

And with that, I'm done with this discussion. By all means continue to retcon and shift goal posts, but the notion that speed doesn't matter w/r/t to energy expenditure is laughable and just plain wrong. Ta ta.
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Old 08-10-21, 03:57 PM
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Originally Posted by david101
Taken out of context, the first statement is indeed incorrect, although perhaps not absurd.
.
Perfect. Let's all move on.
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Old 08-10-21, 04:29 PM
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Originally Posted by WhyFi
fify
If you don't like the phrase, 'taken out of context' don't continue to selectively edit what I wrote.
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Old 08-10-21, 04:31 PM
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Originally Posted by GhostRider62
Perfect. Let's all move on.
Must we? I was really enjoying the discussion. Please feel free to continue to bestow your wisdom upon me.
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Old 08-10-21, 04:54 PM
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Originally Posted by david101

So are you saying that doing something fast does necessarily burn more calories than doing the same thing slowly?
Originally Posted by WhyFi
Yes.
Just saying....
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Old 08-10-21, 04:56 PM
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Just comparing some power meter data from 2 identical loop rides on consecutive days, but at different average speeds:-

Ride 1: Distance 26 km, Av Speed 23.4 kph, Wind speed 26.1 kph SW, Total Work 440 kJ
Ride 2: Distance 26 km, Av Speed 27.1 kph, Wind speed 20.8 kph SSW, Total Work 557 kJ

So for an increase in average speed of just 3.7 kph, Total Work done increased by over 26%

There were no stops in either ride.
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Old 08-10-21, 05:04 PM
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Originally Posted by PeteHski
Just comparing some power meter data from 2 identical loop rides on consecutive days, but at different average speeds:-

Ride 1: Distance 26 km, Av Speed 23.4 kph, Wind speed 26.1 kph SW, Total Work 440 kJ
Ride 2: Distance 26 km, Av Speed 27.1 kph, Wind speed 20.8 kph SSW, Total Work 557 kJ

So for an increase in average speed of just 3.7 kph, Total Work done increased by over 26%

There were no stops in either ride.
That's really interesting, thanks. Those were the kind of numbers that I was looking for.
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Old 08-10-21, 05:17 PM
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Originally Posted by david101
Must we? I was really enjoying the discussion. Please feel free to continue to bestow your wisdom upon me.

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Old 08-10-21, 05:27 PM
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[QUOTE=GhostRider62;22179269] /QUOTE]

Funny, I thought you were an old man. Turns out that you're a teen from 4chan. Or could it be that you actually are an old man, just one who acts like a lonely incel teen posting memes and trolling strangers on the internet? Nahhh, that would be just too sad.
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Old 08-10-21, 05:37 PM
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[QUOTE=david101;22179278]
Originally Posted by GhostRider62
/QUOTE]

Funny, I thought you were an old man. Turns out that you're a teen from 4chan. Or could it be that you actually are an old man, just one who acts like a lonely incel teen posting memes and trolling strangers on the internet? Nahhh, that would be just too sad.
What is 4chan.

As far as trolling, you are the one enjoying spreading misinformation. What you wrote is just wrong, pure and simple. That you enjoyed the ongoing banter tells me who the troll is in this discussion.

I am interested because so many online calculators mislead those trying to lose weight. Someone rides 20 miles and they are told they burned 1400 calories when in fact, they might be lucky to have used half that and probably more like 500 calories. So, they guzzle a fruit smoothie or some sugar energy drink. Then, they can't understand why they do not lose weight. That is basically the gist of this thread. But, you derailed it.
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Old 08-10-21, 05:38 PM
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Originally Posted by PeteHski
Just comparing some power meter data from 2 identical loop rides on consecutive days, but at different average speeds:-

Ride 1: Distance 26 km, Av Speed 23.4 kph, Wind speed 26.1 kph SW, Total Work 440 kJ
Ride 2: Distance 26 km, Av Speed 27.1 kph, Wind speed 20.8 kph SSW, Total Work 557 kJ

So for an increase in average speed of just 3.7 kph, Total Work done increased by over 26%

There were no stops in either ride.
thatís really interesting. how much does the wind speed factor? 5.3kph is a decent difference, but was it a loop?

my loops are oddly shaped and i ALWAYS feel like the wind is blowing straight into me on the long westward stretches, and then when i turn around, iím sheltered by trees and hills and donít get any benefit lol.
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Old 08-10-21, 06:09 PM
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[QUOTE=GhostRider62;22179291]
Originally Posted by david101

I am interested because so many online calculators mislead those trying to lose weight. Someone rides 20 miles and they are told they burned 1400 calories when in fact, they might be lucky to have used half that and probably more like 500 calories. So, they guzzle a fruit smoothie or some sugar energy drink. Then, they can't understand why they do not lose weight. That is basically the gist of this thread. But, you derailed it.
Thanks for writing something in a less confrontational manner. So in the same vein....

Rightly or wrongly, I thought that the OP might be under the misapprehension that by exercising 'harder' to accomplish the same amount of work in a shorter time he was going to burn more calories. My reply, which was the first reply and came before all the technical responses, was merely intended to point out that this wasn't so. I've already acknowledged several times that the point was poorly expressed in my post. Had I appreciated how strong a reaction there would be to quickly dashing out what I thought was a 'fun fact', I would have been much more careful with my wording. Presumably we both know that the reason he burns more calories by cycling faster is because he's done more work to overcome the increased air resistance.

Much of the heat generated later in the thread arose when posters appeared to either deny the validity of my 'faster doesn't necessarily mean more calories' assertion or to disbelieve that that is the point that I had been trying to express in the first place, however clumsily.

Believe it or not, I didn't come into this thread for a fight. All my other interactions on this forum have been very civilised and pleasant. This experience came as a bit of a shock

Last edited by david101; 08-10-21 at 06:23 PM. Reason: had quoted the same post twice
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Old 08-10-21, 06:17 PM
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Originally Posted by david101
I think that you'll find that you haven't answered (or even tried to answer) the question that I asked.
No, I have no intention of doing so.
I don't recognize your authority to assign pointless tasks.
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Old 08-10-21, 06:20 PM
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Originally Posted by david101
I'm not sure to be honest. I only remember one version, but if you're kind enough to show me the others I will count them for you.
No thanks. I don't expect your math to be any better than your logic.

​​​​​​
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Old 08-10-21, 06:26 PM
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Originally Posted by livedarklions
No thanks. I don't expect your math to be any better than your logic.

​​​​​​
More abuse just after I'd tried to make nice. I'll refrain from responding in kind.
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Old 08-10-21, 08:07 PM
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Originally Posted by david101
That's really interesting, thanks. Those were the kind of numbers that I was looking for.
I posted back in post #322 a ride of equal distance where the faster ride took 82% more energy. For clarification, the route is an out and back that's mostly flat with low wind.
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Old 08-10-21, 08:18 PM
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Originally Posted by GhostRider62
860 calories in an hour implies an average power of around 240-250 watts. This would take a lot of fitness to achieve. To only go 15 mph on 240-250 watts would mean either a stiff headwind or uphill the whole way.

I would estimate that you needed an average of 100-105 watts for 15 mph and you burned 180-200 calories in half an hour, at the most.
Yes.
Online cyclists seem to be averaging at least 200 watts or more. In real life, the cycle club riders I know are likely in the 120-150 watt range. They can ride 50 miles and 3000 feet of elevation pretty easily, but at a moderate pace.

The 200-250 watt riders are twice as fast on hills and are often averaging over 20 mph on their somewhat flatter rides. There's quite a few of them, but even more of the slower riders. Still, even 100 watts average for an hour is difficult for lots of casual riders -- it takes some practice to hold a steady enough pace -- casual riders often do a small burst of energy, then coast and repeat.

The rule of thumb I've seen and experienced is around 20-25 calories per mile. It's surprising to me how often this works out for me, and adding some climbs doesn't really change the numbers most of the time. I would reach the low 30 cal per mile range with a strong-for-me steadily hard effort. Of course, wind, rider weight, etc, all factor in. But my powermeter just shows the actual power I'm using, which readily converts into fairly accurate calories.
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Old 08-10-21, 08:31 PM
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Originally Posted by rm -rf
The rule of thumb I've seen and experienced is around 20-25 calories per mile. It's surprising to me how often this works out for me, and adding some climbs doesn't really change the numbers most of the time. I would reach the low 30 cal per mile range with a strong-for-me steadily hard effort. Of course, wind, rider weight, etc, all factor in. But my powermeter just shows the actual power I'm using, which readily converts into fairly accurate calories.
i’m curious is anyone has seen studies on the “efficiency” of one cyclist to another. is a well trained cyclist much more efficient - less calories per watt? all the references to the figure I’ve seen are pretty absolute, and it surprises me that it wouldn’t be highly variable.

FWIW, my calories per mile seems to average around 45. 50-100 feet of climbing per mile. 220lb total weight including bike, clothes, water, me. average speed almost always 15mph +/- 1.

Human efficiency is only 24%

Another problem is that humans aren’t perfectly efficient engines. We spend a lot of energy on heat production, balance and other things while riding a bike. In fact, efficiency of cycling humans is around 25%. We burn 5 joules of energy for each joule delivered to the pedals. That means we should divide the measured joules by 0.25 to calculate the actual expenditure. By coincidence, the joule to kcal conversion mentioned above is 0.2389. So, the last two problems cancel each other out, and we can just swap joules for kcal.

Last edited by mschwett; 08-10-21 at 08:36 PM.
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Old 08-11-21, 04:57 AM
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Originally Posted by david101
More abuse just after I'd tried to make nice. I'll refrain from responding in kind.
If this sorry lashing out is "making nice" to you, I'll be putting you on my ignore list. Bye.
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Old 08-11-21, 05:06 AM
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Originally Posted by mschwett
thatís really interesting. how much does the wind speed factor? 5.3kph is a decent difference, but was it a loop?

my loops are oddly shaped and i ALWAYS feel like the wind is blowing straight into me on the long westward stretches, and then when i turn around, iím sheltered by trees and hills and donít get any benefit lol.
Yes it was a simple loop. The wind speed would have had some non-linear effect, but it wasnít the reason for the difference in average speed. The first ride was strictly a recovery ride and the second was a base ride. I found a third faster ride on the same loop to add:-

3. Av Speed 30.2 kph, Wind 14.5 kph SE, Total Work 608 kJ

So much less wind than the other rides, but yet more work done at the higher speed.

Av Power vs Av Speed for those 3 rides was:-

1. Power 111W, Speed 23.4 kph
2. Power 162W, Speed 27.1 kph
3. Power 197W, Speed 30.2 kph

Terrain was rolling hills with a few short moderately steep climbs. Notably less windy on ride 3.

Last edited by PeteHski; 08-11-21 at 05:26 AM.
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