Longer crank arms = less force in pedaling?
03-02-06, 03:37 PM
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Longer crank arms = less force in pedaling?
I used Sheldon Brown's gear inch calculator, and the length of the cranks made no difference in the gear inches.
But physics says that the longer the lever arm, the more you're moving but the less force you're putting in.
So if I go to a 165 to a 172.5mm crank length, it will be easier to pedal?
But physics says that the longer the lever arm, the more you're moving but the less force you're putting in.
So if I go to a 165 to a 172.5mm crank length, it will be easier to pedal?
03-02-06, 03:39 PM
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shorter cranks = easier spinning but less leverage.
you would probably like to spin more in a flat city, but need the leverage more in a hilly city.
you would probably like to spin more in a flat city, but need the leverage more in a hilly city.
03-02-06, 03:43 PM
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Originally Posted by BostonFixed
shorter cranks = easier spinning but less leverage.
you would probably like to spin more in a flat city, but need the leverage more in a hilly city.
you would probably like to spin more in a flat city, but need the leverage more in a hilly city.
03-02-06, 03:46 PM
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Originally Posted by jacobpriest
dont you mean this the other way? because going up hills on a road bike you gear down so you can keep spinning at the same pace and make it as hard. with more leverage in a hilly city, i would think you would have to work harder, opposed to a flat city you can use more leverage and be able to get going faster because no uphills. **********?
03-02-06, 03:56 PM
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Yes, a longer crank arm will require less force pushing down and pulling up on the pedals to make the same power. However, you are making up for the lower pedal force by applying the pedal force over a longer stroke. Work = Force X distance
crank arm length is not a variable in the gear inches calculation. But a longer crank can allow you to use a taller gear inch combination
03-02-06, 03:58 PM
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gear inches is what the diameter the wheel would be on a penny farthing ( 1:1 ratio direct drive) to achieve the same distance travelled for one crank rotation. therefore even if your cranks were 50cm long it would still only be for one rotation, however much easier that rotation is made by the extra leverage.
03-02-06, 04:06 PM
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aye, gear inches just isn't a measurement that cares about crank length, regardless of its effects. sheldon brown pushes "gain ratios," which, not to be confused with simple front/back ratios, take into account the crank length as well as wheel size and gear ratio.
03-02-06, 05:31 PM
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If you're tall tho (like 6'2") you may be more comfortable with a 170-180.
03-02-06, 05:38 PM
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Originally Posted by salmonchild
therefore even if your cranks were 50cm long it would still only be for one rotation, however much easier that rotation is made by the extra leverage.
03-02-06, 08:39 PM
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Shorter cranks make it easier to go downhill fast and harder to go uphill at any speed.
It makes more sense if one takes it to an absurd extreme and imagines one inch cranks.
No matter how fast one goes downhill with one inch cranks, his pedals will still go around the same number of times per wheel revolution, but they will only move up and down two inches while traveling a 6.28 inch circle.
Now, take it to the other extreme, and imagine 330mm, or 13 inch cranks.
No matter how fast one goes downhill with 13 inch cranks, his pedals will still go around the same number of times per wheel revolution, but they will go up and down 26 inches while traveling an 81.7 inch circle.
It makes more sense if one takes it to an absurd extreme and imagines one inch cranks.
No matter how fast one goes downhill with one inch cranks, his pedals will still go around the same number of times per wheel revolution, but they will only move up and down two inches while traveling a 6.28 inch circle.
Now, take it to the other extreme, and imagine 330mm, or 13 inch cranks.
No matter how fast one goes downhill with 13 inch cranks, his pedals will still go around the same number of times per wheel revolution, but they will go up and down 26 inches while traveling an 81.7 inch circle.
