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Old 02-11-07, 02:25 AM   #1
Wheelchairman
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What dictates a chain's efficiency?

Is weight the only factor? Does materials and the shape of the link matter?

Awaiting reply!
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Old 02-11-07, 05:27 AM   #2
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Just what do you mean by efficiency? Are you talking about power loss during the transfer process or you asking about shifting crispness?

Either way I'm interested in what the engineering guys are going to have to say. If we're lucky maybe Sheldon will weigh in on this question. I honestly don't know so anything I say would just be a guess.
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Old 02-11-07, 05:49 AM   #3
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Whoops. Should've been more specific

I'd like to think that shifting is a distant 2nd on my priorities.

I guess I'm talking about power lost during transfer, but from a feeling point of view, I'm talking specifically about ease of pedaling. You know what I mean. A chain that gives the impression that you could pedal on at X cadence forever without a break.
Is this dictated just by the weight, or does shape and materials contribute as well?
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Old 02-11-07, 06:45 AM   #4
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Quote:
Originally Posted by Wheelchairman
Whoops. Should've been more specific

I'd like to think that shifting is a distant 2nd on my priorities.

I guess I'm talking about power lost during transfer, but from a feeling point of view, I'm talking specifically about ease of pedaling. You know what I mean. A chain that gives the impression that you could pedal on at X cadence forever without a break.
Is this dictated just by the weight, or does shape and materials contribute as well?
Chain offer extremely diminishing returns, the thing that helps the most will be constantly keeping the chain well lubed and clean of dirt. Helping both the chain's longevity and it's efficiency.
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Old 02-11-07, 09:13 AM   #5
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Quote:
Originally Posted by Wheelchairman
Whoops. Should've been more specific

I'd like to think that shifting is a distant 2nd on my priorities.

I guess I'm talking about power lost during transfer, but from a feeling point of view, I'm talking specifically about ease of pedaling. You know what I mean. A chain that gives the impression that you could pedal on at X cadence forever without a break.
Is this dictated just by the weight, or does shape and materials contribute as well?
The ease of peadling or the "effiency" you feel is all about the "ratio (sprocket combination), load (weight and the grade if a hill you may be riding on), current road speed, and lastley your physical energy at that particular moment.
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Old 02-11-07, 09:19 AM   #6
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Friction is the only loss that occurs in chains. Keep it clean and lubed and you are good to go.
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Old 02-11-07, 09:42 AM   #7
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From the book "Bicycling Science" by Wilson, 3rd edition, 2004, MIT Press, pg 317:

"Despite the importance of drive chain to bicycles and especially to industrial equipment, published research on it has been spotty, Some of the best work is secreted in manufactureres' vaults or stored in the minds of retired engineers, because there is no present commercial value to aplying or disseminating it."

Futher, the book references a Ph D dissertation by Mathew Kidd (Department of Mechanical Engineering at Heriot-Watt University, Edinburgh, Scotland) as a complete compilation of the available literature on efficiency and on the effects of tooth form.

From "Design of Machine Elements" by Spotts, 6th edition, pg 321, relates horsepower capacity to the fatigue life of the link plates (for lower speeds) and to fatigue life of the roller bearing (for higher speeds). These formulas seem highly experimental. For example, the former relates horsepower to:

N (number of teeth in the smaller sprocket) raised to the 1.08 power,
n, (rpm of the smaller sprocket) raised to the 0.9 power
p (pitch) raised to the (3-.07p) power


I'm hoping others have more definitive information.
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Old 02-11-07, 11:55 AM   #8
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Originally Posted by MudPie
From the book "Bicycling Science" by Wilson, 3rd edition, 2004, MIT Press, pg 317:

"Despite the importance of drive chain to bicycles and especially to industrial equipment, published research on it has been spotty, Some of the best work is secreted in manufactureres' vaults or stored in the minds of retired engineers, because there is no present commercial value to aplying or disseminating it."

Futher, the book references a Ph D dissertation by Mathew Kidd (Department of Mechanical Engineering at Heriot-Watt University, Edinburgh, Scotland) as a complete compilation of the available literature on efficiency and on the effects of tooth form.

From "Design of Machine Elements" by Spotts, 6th edition, pg 321, relates horsepower capacity to the fatigue life of the link plates (for lower speeds) and to fatigue life of the roller bearing (for higher speeds). These formulas seem highly experimental. For example, the former relates horsepower to:

N (number of teeth in the smaller sprocket) raised to the 1.08 power,
n, (rpm of the smaller sprocket) raised to the 0.9 power
p (pitch) raised to the (3-.07p) power


I'm hoping others have more definitive information.
Nope, I dought they would. Might as well do my own research. Seems that's all the info I'm going to get. Thanx for the info, mudpie. It's a start!

I ride HPV's, and thus we use 3 lengths of chain. Chainweight is obviously tripled, so I thought it'd be nice to know wether the efficentcy we get through our chains can be performed with heavier chains- that may indicate that weight is only one of the factors if so! Thought I'd come here 1st before doing that.
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Old 02-11-07, 12:05 PM   #9
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Originally Posted by Wheelchairman
Nope, I dought they would. Might as well do my own research. Seems that's all the info I'm going to get. Thanx for the info, mudpie. It's a start!

I ride HPV's, and thus we use 3 lengths of chain. Chainweight is obviously tripled, so I thought it'd be nice to know wether the efficentcy we get through our chains can be performed with heavier chains- that may indicate that weight is only one of the factors if so! Thought I'd come here 1st before doing that.
The main things that determine chain efficience are chainline, sprocket size and sprocket ratio.

Straight chainline is best, efficiency goes down considerably with crooked chainline.

Larger sprockets are very slightly more efficient than smaller ones.

Greatest efficiency occurs with 1:1 gearing, but this fact is not particularly useful for bicycle applications.

For recumbents, chainline isn't generally an issue, since the chain is so long. The thing that kills drivetrain efficiency in most recumbents is the use of an idler pulley in the taut (upper) run of the chain. If you're fussy about efficiency, this is an area to concentrate on.

Sheldon "Greenspeed" Brown
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