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Author Topic: How would you compare the efficiency of cycling and walking?  (Read 7991 times)

Reg

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Reg asked the Naked Scientists:
   
Hi,

I have often wondered how one might calculate the difference in the efficiency of walking and bicycling.

What do you think?


 

Offline Madidus_Scientia

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How would you compare the efficiency of cycling and walking?
« Reply #1 on: 28/10/2009 17:53:35 »
I think energy expenditure of an activity can be roughly calculated based on the difference between a subjects resting heart rate and their heart rate during exercise, their weight and the duration. No idea what the formula is, but if you then monitored the same subject while walking and while cycling you should get the data you need.

That's in terms of energy, but it could be made alot more simple in terms of time, if it takes 2 minutes to cycle what would take 10 minutes walking then cycling would be 500% more efficient.

Or maybe you could get the subject to do each exercise in a small airtight room and then analyze a sample of the air afterwards to see how much the O2/CO2 concentrations changed, which should be alot more accurate. (I guess you would have to make sure the air is well mixed though so the gases evenly distribute)
« Last Edit: 28/10/2009 17:55:49 by Madidus_Scientia »
 

Offline Karsten

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How would you compare the efficiency of cycling and walking?
« Reply #2 on: 29/10/2009 00:37:51 »
I wanted to ask a very similar question but I kept forgetting it:

Is it more efficient to ride your bike up a steep hill or push it up that hill?

Now, since we are discussing how to measure efficiency of the two modes of transportation, maybe this could be answered as well.
 

Offline Madidus_Scientia

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How would you compare the efficiency of cycling and walking?
« Reply #3 on: 31/10/2009 05:38:12 »
Well since no one else answered i'll have a crack at it, I reckon it is more efficient to walk it up steep hills because you can apply more power that way. Unless you had a really really low-geared bike, but then you'd probably be going so slow you'd fall over anyway.
 

Offline Karsten

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How would you compare the efficiency of cycling and walking?
« Reply #4 on: 31/10/2009 18:07:58 »
Well since no one else answered i'll have a crack at it, I reckon it is more efficient to walk it up steep hills because you can apply more power that way. Unless you had a really really low-geared bike, but then you'd probably be going so slow you'd fall over anyway.

Well, a decent mountain bike has a less than 1:1 gear ratio and it ends up being similar to walking speed when going up the hill I have in mind. Why can I apply more power when walking? I can imagine that pedaling includes overcoming the friction of the chain, chain wheels, etc. but maybe that efficiency decrease is made up by an increase in efficiency due to a more efficient muscle use. I don't know. It probably comes down to oxygen use again.
 

Offline Madidus_Scientia

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How would you compare the efficiency of cycling and walking?
« Reply #5 on: 01/11/2009 01:23:33 »
You have more traction walking, you're not fighting the tendency to roll backwards. A pedestrian would always win a tug of war against a cyclist.
 

Offline techmind

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How would you compare the efficiency of cycling and walking?
« Reply #6 on: 01/11/2009 22:46:05 »
I'm no health or fitness expert, but I would have thought that measuring exhaled CO2 volume would give a fairly accurate picture of energy use minute by minute. You could probably do this with a backpack sized instrument or smaller.

You'd need to compare the total exhaled CO2 over the distance of the course, for both modes of transport, and at rest, as a baseline.

You might get a similar (but less-accurate?) result counting the total number of heartbeats over the course - someone who's a medic, cardiologist or something probably has a better idea.


Going up a steep hill, there might not be so much difference between cycling and walking, but on the level (or even downhill!) cycling is going to win easily.
 

Offline FuzzyUK

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How would you compare the efficiency of cycling and walking?
« Reply #7 on: 04/11/2009 07:53:43 »
Quote
I have often wondered how one might calculate the difference in the efficiency of walking and bicycling.

I had a heart attack many years ago and I was summoned to do some walking exercises only a week after. I rarely walk and felt totally alienated with the unpleasant experience of footing it 400 yards to the supermarket. I carefully  measured my maximum pulse rate whilst doing so and the next day I jumped on my bike and steamed away until my ticker got up to similar speed. I found I could do a couple of miles or so of peddling for the same amount of effort as walking.

It's not quite a scientific way of measuring efficiency but it helps gets things in perspective. Another way of looking at it is that I can at present walk 3 miles in one hour, and cream off 15 on a bike.

I still travel around Cambridge by bike and aim to do 5-10 miles every day or two. Last year I managed a couple of 60 mile day rides back from the coast. I've never had a car and am in my early sixties.
 

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How would you compare the efficiency of cycling and walking?
« Reply #7 on: 04/11/2009 07:53:43 »

 

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