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I know somebody can help me out on this one. Sorry if it's been posted before.

I want to calculate the force of a pedal stroke. More specifically I want to find the difference of a 53-12 combination vs. a 50-12 combination. I know it's easy to come up with the ratios and figure the difference. But I want to relate that difference into actual enegry expediture difference.

Hope that make sense....:confused: :eek:
 

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BeerBike said:
I know somebody can help me out on this one. Sorry if it's been posted before.

I want to calculate the force of a pedal stroke. More specifically I want to find the difference of a 53-12 combination vs. a 50-12 combination. I know it's easy to come up with the ratios and figure the difference. But I want to relate that difference into actual enegry expediture difference.

Hope that make sense....:confused: :eek:

The short answer is under the same conditions, going the same speed, the energy expenditure will be the same.

For a longer answer, start here - http://www.analyticcycling.com/ , take a look at the "Static Forces on Rider" ->"Power, Given Speed" in the menu on the right.
 

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BeerBike said:
I want to calculate the force of a pedal stroke. More specifically I want to find the difference of a 53-12 combination vs. a 50-12 combination. I know it's easy to come up with the ratios and figure the difference. But I want to relate that difference into actual enegry expediture difference.
http://home.earthlink.net/~acoggan/quadrantanalysis/
But be clear on the differences between force, energy (work), and power
 

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Helpful website.

I would like to thank you for sharing such a helpful website. I ran the gear selection calculator and was very impressed! How many calories would a power output of 1488 watts translate to? Thanks.
Dr. Paul Proteus said:
The short answer is under the same conditions, going the same speed, the energy expenditure will be the same.

For a longer answer, start here - http://www.analyticcycling.com/ , take a look at the "Static Forces on Rider" ->"Power, Given Speed" in the menu on the right.
 

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Energy, power

ru1-2cycle said:
I would like to thank you for sharing such a helpful website. I ran the gear selection calculator and was very impressed! How many calories would a power output of 1488 watts translate to? Thanks.
I think you're confusing power and energy. Energy (which can be expressed in calories or Joules) is the amount of work that is done. Power (which can be expressed as Watts) is how fast that energy is delivered (i.e. energy delivered per unit time).

1 calorie = 4.1868 Joules
1 Joule = 0.2388 calories
1 Watt = 1 Joule/sec. = 0.2388 calories/Sec.

So, the number of calories required to output 1488 Watts depends on how long that power is produced.

Note 1: Food energy is usually measured as Calories = Kcalories = 1000 calories (i.e. a Calorie with a big 'C' is a thousand times larger than a calorie with a small 'c').

Note 2: The human body is only about 25% efficient at converting food energy into mechanical work, so 1 food calorie generates approximately 1 Joule of mechanical work by the body, or 1 Calorie (Kilocalorie) consumed by the body is about 1000 Joules of mechanical work. So generating 1488 Watts requires about 1488 calories/second = 1.488 Calories/second.

Note 3: 1488 Watts is a huge amount of power for a human to generate. Power this large is only generated by the strongest sprinters, and then for only a few seconds.
 
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