New study shows leg flexion less efficient than extension.

[JamesCun]

Yes Frank, we agree that a counterweight was used in the OP. We also agree that no counterweight can ever exist with uncoupled cranks.

Glad we reached that agreement. Not sure why you protested so long.

 

[Irondan]

The only posts that have been deleted are the ones that have nothing to do with the topic, or the discussion. Please keep to the forum rules.

 

[FrankDay]

Re:

We also agree that no counterweight can ever exist with uncoupled cranks.

Since this was not deleted with all the others I would like to reiterate that we do not agree on this.

 

[JamesCun]

Re: Re:

We also agree that no counterweight can ever exist with uncoupled cranks.

Since this was not deleted with all the others I would like to reiterate that we do not agree on this.

That is fine. There is no debate possible on this topic. No counterweight exists with uncoupled cranks.

From Wikipedia:
A counterweight is an equivalent counterbalancing weight that balances a load. Its purpose is to make lifting the load more efficient, which saves energy and is less taxing on the lifting machine. Counterweights are often used in traction lifts (elevators), cranes and funfair rides.

 

[FrankDay]

Re: Re:

We also agree that no counterweight can ever exist with uncoupled cranks.

Since this was not deleted with all the others I would like to reiterate that we do not agree on this.

That is fine. There is no debate possible on this topic. No counterweight exists with uncoupled cranks.

From Wikipedia:
A counterweight is an equivalent counterbalancing weight that balances a load. Its purpose is to make lifting the load more efficient, which saves energy and is less taxing on the lifting machine. Counterweights are often used in traction lifts (elevators), cranes and funfair rides.

The only issue I take with the Wikipedia definition is the word equivalent. A counterweight is not always (in fact not usually, the elevator is an example) an equivalent balancing weight, that would be a counterbalancing weight.

 

[JamesCun]

Re: Re:

We also agree that no counterweight can ever exist with uncoupled cranks.

Since this was not deleted with all the others I would like to reiterate that we do not agree on this.

That is fine. There is no debate possible on this topic. No counterweight exists with uncoupled cranks.

From Wikipedia:
A counterweight is an equivalent counterbalancing weight that balances a load. Its purpose is to make lifting the load more efficient, which saves energy and is less taxing on the lifting machine. Counterweights are often used in traction lifts (elevators), cranes and funfair rides.

The only issue I take with the Wikipedia definition is the word equivalent. A counterweight is not always (in fact not usually, the elevator is an example) an equivalent balancing weight, that would be a counterbalancing weight.

So we agree on what a counterweight is and therefore agree that uncoupled cranks can never be a counterweight. It doesn't matter if you think a counterweight is 100% of the weight or 10%, it can't exist in an uncoupled system. A crank that isn't attached can't act to balance the other crank.

 

[FrankDay]

Re: Re:

We also agree that no counterweight can ever exist with uncoupled cranks.

Since this was not deleted with all the others I would like to reiterate that we do not agree on this.

That is fine. There is no debate possible on this topic. No counterweight exists with uncoupled cranks.

From Wikipedia:
A counterweight is an equivalent counterbalancing weight that balances a load. Its purpose is to make lifting the load more efficient, which saves energy and is less taxing on the lifting machine. Counterweights are often used in traction lifts (elevators), cranes and funfair rides.

The only issue I take with the Wikipedia definition is the word equivalent. A counterweight is not always (in fact not usually, the elevator is an example) an equivalent balancing weight, that would be a counterbalancing weight.

So we agree on what a counterweight is and therefore agree that uncoupled cranks can never be a counterweight. It doesn't matter if you think a counterweight is 100% of the weight or 10%, it can't exist in an uncoupled system. A crank that isn't attached can't act to balance the other crank.

Nope. when there is positive force around the entire circle with uncoupled cranks the shafts behave as if they are fused together. While no energy transfer can take place the counterweight of the other leg effectively eases the work of the upcoming leg by helping to maintain pedal speed, making making maintaining pedal speed on the upstroke more efficient, the role of a counterweight according to your definition. Sorry but it is how an engineer looks at the problem.

 

[JamesCun]

Re: Re:

Nope. when there is positive force around the entire circle with uncoupled cranks the shafts behave as if they are fused together. While no energy transfer can take place the counterweight of the other leg effectively eases the work of the upcoming leg by helping to maintain pedal speed, making making maintaining pedal speed on the upstroke more efficient, the role of a counterweight according to your definition. Sorry but it is how an engineer looks at the problem.

So a motor on your bike would also be a counterweight? It would help maintain pedal speed and reduce the effort needed on the upstroke.

And, they only behave as if they were fused in one direction. If force is applied in the opposite direction, they act like a limp string. Hence no counterweight and no balancing possible.

 

[FrankDay]

Re: Re:

Nope. when there is positive force around the entire circle with uncoupled cranks the shafts behave as if they are fused together. While no energy transfer can take place the counterweight of the other leg effectively eases the work of the upcoming leg by helping to maintain pedal speed, making making maintaining pedal speed on the upstroke more efficient, the role of a counterweight according to your definition. Sorry but it is how an engineer looks at the problem.

So a motor on your bike would also be a counterweight? It would help maintain pedal speed and reduce the effort needed on the upstroke.

And, they only behave as if they were fused in one direction. If force is applied in the opposite direction, they act like a limp string. Hence no counterweight and no balancing possible.

Well, a motor behaves sort of as a counterweight (it aids the entire circle not just half) but it isn't strictly one. It is the old thought experiment of Einstein about gravity. If in a box and can't see out one cannot tell if one is in an accelerating elevator, rocket ship, or gravitational field as they all feel the same even though they are different.

 

[PhitBoy]

Re: Re:

I'm an Engineer (BSME from UT Austin) and no engineer I know would look at the system that way.
What you describing is a propulsive torque from the flexing leg. Not a counterweight at all.
Perhaps, as I suggested in an earlier post, you could draw a free body diagram so we can try to understand what you're thinking. Then we can figure out where your reasoning is going off track.

when there is positive force around the entire circle with uncoupled cranks the shafts behave as if they are fused together. While no energy transfer can take place the counterweight of the other leg effectively eases the work of the upcoming leg by helping to maintain pedal speed, making making maintaining pedal speed on the upstroke more efficient, the role of a counterweight according to your definition. Sorry but it is how an engineer looks at the problem.

 

[FrankDay]

Re: Re:

I'm an Engineer (BSME from UT Austin) and no engineer I know would look at the system that way.
What you describing is a propulsive torque from the flexing leg. Not a counterweight at all.
Perhaps, as I suggested in an earlier post, you could draw a free body diagram so we can try to understand what you're thinking. Then we can figure out where your reasoning is going off track.

when there is positive force around the entire circle with uncoupled cranks the shafts behave as if they are fused together. While no energy transfer can take place the counterweight of the other leg effectively eases the work of the upcoming leg by helping to maintain pedal speed, making making maintaining pedal speed on the upstroke more efficient, the role of a counterweight according to your definition. Sorry but it is how an engineer looks at the problem.

It would be a waste of effort to this group. The counterweight is the weight of the downward leg adding to the propulsive force helping to maintain pedal speed. Has nothing to do with the "propulsive torque from the flexing leg". That is what keeps the "shafts" fused.

edit: what determines whether it behaves as a counterweight or not is the math. The math is the same for both conditions, coupled and uncoupled, as long as the pedal speeds are equal, which requires constant propulsive force on each crank for the entire circle. Do the math.

 

[JamesCun]

Re: Re:

I'm an Engineer (BSME from UT Austin) and no engineer I know would look at the system that way.
What you describing is a propulsive torque from the flexing leg. Not a counterweight at all.
Perhaps, as I suggested in an earlier post, you could draw a free body diagram so we can try to understand what you're thinking. Then we can figure out where your reasoning is going off track.

when there is positive force around the entire circle with uncoupled cranks the shafts behave as if they are fused together. While no energy transfer can take place the counterweight of the other leg effectively eases the work of the upcoming leg by helping to maintain pedal speed, making making maintaining pedal speed on the upstroke more efficient, the role of a counterweight according to your definition. Sorry but it is how an engineer looks at the problem.

It would be a waste of effort to this group. The counterweight is the weight of the downward leg adding to the propulsive force helping to maintain pedal speed. Has nothing to do with the "propulsive torque from the flexing leg". That is what keeps the "shafts" fused.

edit: what determines whether it behaves as a counterweight or not is the math. The math is the same for both conditions, coupled and uncoupled, as long as the pedal speeds are equal, which requires constant propulsive force on each crank for the entire circle. Do the math.

The fact that one leg helps the other doesn't mean it is a counterweight. The cranks are not able to directly transfer energy, therefor they are not counterweights. Having a similar affect doesn't mean they are the same thing. My example of a motor on the bike clearly illustrated how you don't understand the concept.

 

[PhitBoy]

Re: Re:

No engineer would say that the system you are describing is a counterweight system.
If you can draw the FBD that shows how you believe this system works perhaps I and others can help you see where you are getting it wrong.

It would be a waste of effort to this group. The counterweight is the weight of the downward leg adding to the propulsive force helping to maintain pedal speed. Has nothing to do with the "propulsive torque from the flexing leg". That is what keeps the "shafts" fused.

edit: what determines whether it behaves as a counterweight or not is the math. The math is the same for both conditions, coupled and uncoupled, as long as the pedal speeds are equal, which requires constant propulsive force on each crank for the entire circle. Do the math.

 

[FrankDay]

Re: Re:

No engineer would say that the system you are describing is a counterweight system.
If you can draw the FBD that shows how you believe this system works perhaps I and others can help you see where you are getting it wrong.

It would be a waste of effort to this group. The counterweight is the weight of the downward leg adding to the propulsive force helping to maintain pedal speed. Has nothing to do with the "propulsive torque from the flexing leg". That is what keeps the "shafts" fused.

edit: what determines whether it behaves as a counterweight or not is the math. The math is the same for both conditions, coupled and uncoupled, as long as the pedal speeds are equal, which requires constant propulsive force on each crank for the entire circle. Do the math.

Visualize three systems.

1. a coupled system where the rider is doing a single leg pedaling drill and pulling up at 9 o'clock with 22 lbs on 6 inch cranks and there is no weight on the left crank at 3 o'clock. The chain rings are seeing 11 ft-lbs torque.
2. A coupled system with 6 in cranks where the rider is riding with both legs and the left leg at 3 o'clock weighs and is exerting 20 lbs force down on the left pedal which then, because of the coupling, exerts 20 lbs force up on the right pedal in the 9 o'clock position. All the rider need do is pull up an additional 2 lbf on that right crank and the chain rings see 11 ft-lbs torque from the counterweight (the weight of the left leg) and the pulling up by the right leg. The counterweight eased the work required of the "recovery" leg. It makes no difference how hard the rider pushes down with the left leg here as the weight component does not change.
3. An uncoupled system where the rider is riding with both legs and the left leg at 3 o'clock weighs and is exerting 20 lbs force down on the left pedal which then, because of the un-coupling, cannot exert the 20 lbs force up on the right pedal in the 9 o'clock position that the coupled system does so instead, the force goes to the chain rings. All the rider need do is pull up an additional 2 lbf on that right crank and, again, the chain rings see 11 ft-lbs torque from the combination of the counterweight (the weight of the left leg) and the pulling up by the right leg. The counterweight eased the work required of the "recovery" leg. It makes no difference how hard the rider pushes down with the left leg here as the weight component does not change.

Three systems with the same result but from the point of view of the rider and the bicycle neither the bike nor the rider can tell whether the BB system is uncoupled or coupled and, hopefully, now you can see why I say the uncoupled system is "aided" by the counterweight when applying some force around the entire circle. The math is the same so the conclusion is the same, it does.

I look forward to your instructing me as to where my analysis is wrong.

 

[JamesCun]

Frank, having a similar impact doesn't make two different concepts the same. There is no counterweight with uncoupled cranks.

 

[PhitBoy]

Re: Re:

I look forward to your instructing me as to where my analysis is wrong.

You seem to be using muscular and gravity dependent terms interchangeably and describing how they produce torque, which makes the scenarios seem much more complicated than they really are.
With a counter-weighted system, such as bilateral pedaling or single leg with a counterweight, the cyclist is free to choose when and where to produce muscular force. No upward muscular force is required during flexion to lift the leg because the weight of the flexing leg is balanced by the contralateral leg or the counter-weight. Conversely, in the uncoupled or single leg non counter-weighted system, the cyclist must lift the weight of the leg during the flexion phase or else the pedal will simply not come up.
To use the teeter totter analogy, just because one kid "can" stand up and sit down alone on a teeter totter, that is not the same as playing with another kid on the other end.

 

[King Boonen]

Re: Re:

If the p-value is the probability of whatever is being measured not being due to chance...

Again, this is incorrect. The p-value is the likelihood of it occuring if it IS ONLY DUE TO CHANCE.

From the link you posted, again:

The p-value is not the probability that the null hypothesis is true or the probability that the alternative hypothesis is false. It is not connected to either. In fact, frequentist statistics does not and cannot attach probabilities to hypotheses. Comparison of Bayesian and classical approaches shows that a p-value can be very close to zero and the posterior probability of the null is very close to unity (if there is no alternative hypothesis with a large enough a priori probability that would explain the results more easily), Lindley's paradox. There are also a priori probability distributions bin which the posterior probability and the p-value have similar or equal values.[18]

 

[King Boonen]

Re: Re:

...
This is true Jay, notice it only refers to the result under a certain condition, it does not refer to the likelihood of a hypothesis being true or false,
...
He was attempting to use the p-value to assign a probability that the hypothesis is true. This is categorically wrong. This statistic cannot attach probabilities to hypotheses. This is clearly stated in the article:

--------------------------------------------------
I agree, it's a complex and subtle difference (well to me anyhow...) that the
p-value indicates the likelihood of the TEST DATA being obtained WHEN the null hypothesis is TRUE.
And NOT that the p-value (from the test data) indicates the likeliness of the null hypothesis BEING true.

Jay Kosta
Endwell NY USA

We all agree with this although I think you should substitute IF for WHEN.

No. There is no THINK about it. It is ONLY applicable WHEN the null hypothesis is true.

 

[FrankDay]

Re: Re:

I look forward to your instructing me as to where my analysis is wrong.

You seem to be using muscular and gravity dependent terms interchangeably and describing how they produce torque, which makes the scenarios seem much more complicated than they really are.

Now let me get this straight, you have a mechanical engineering degree and you are criticizing my analysis because I am considering force that comes from a gravitational source similar to a force coming from a muscular force? Is that correct?

With a counter-weighted system, such as bilateral pedaling or single leg with a counterweight, the cyclist is free to choose when and where to produce muscular force. No upward muscular force is required during flexion to lift the leg because the weight of the flexing leg is balanced by the contralateral leg or the counter-weight. Conversely, in the uncoupled or single leg non counter-weighted system, the cyclist must lift the weight of the leg during the flexion phase or else the pedal will simply not come up.

And then you criticize my analysis because in the coupled system the cyclist is free to not lift the leg even though nothing prevents him from doing so? You do realize that pulling up is a constraint on the system being analyzed? My analysis shows the systems to act similarly when the riders are pedaling similarly as required by the uncoupled system. When pedaling as an uncoupled system requires it is not possible for any observer to tell if the rider is on an uncoupled or coupled system. They (and the counterweight) work identically.

To use the teeter totter analogy, just because one kid "can" stand up and sit down alone on a teeter totter, that is not the same as playing with another kid on the other end.

Irrelevant.

 

[King Boonen]

Re: Re:

I didn't say you mentioned the null hypothesis but you don't have to as you are attempting to assign a percentage to the chance of differences being real based on a p-value.
You keep making this false statement that I have bolded, it does nothing of the kind and this has been pointed out to you over and over. Yet more trolling.

Frank is a lost cause when it comes to discussion free of logical fallacies.

Indeed I play a game of logical fallacy bingo when Frank posts. It can be quite entertaining.

My posts aren't really to educate Frank. I fully believe he is being wilfully deceitful as he keeps referencing a link that proves him wrong. They are for the benefit of people who might get taken in by the rubbish he is talking.

 

[King Boonen]

Re:

...
This is true Jay, notice it only refers to the result under a certain condition, it does not refer to the likelihood of a hypothesis being true or false,
...
He was attempting to use the p-value to assign a probability that the hypothesis is true. This is categorically wrong. This statistic cannot attach probabilities to hypotheses. This is clearly stated in the article:

--------------------------------------------------
I agree, it's a complex and subtle difference (well to me anyhow...) that the
p-value indicates the likelihood of the TEST DATA being obtained WHEN the null hypothesis is TRUE.
And NOT that the p-value (from the test data) indicates the likeliness of the null hypothesis BEING true.

Jay Kosta
Endwell NY USA

It's complex, subtle and very straight forward at the same time which is usually the problem. It's the most mis-used statistic in science too probably because it is so easy to calculate and claim it says what you want it to say. It's fine for people to say they don't get it, it's not fine for people to abuse it and think they can get away with it.

 

[FrankDay]

Re: Re:

...
This is true Jay, notice it only refers to the result under a certain condition, it does not refer to the likelihood of a hypothesis being true or false,
...
He was attempting to use the p-value to assign a probability that the hypothesis is true. This is categorically wrong. This statistic cannot attach probabilities to hypotheses. This is clearly stated in the article:

--------------------------------------------------
I agree, it's a complex and subtle difference (well to me anyhow...) that the
p-value indicates the likelihood of the TEST DATA being obtained WHEN the null hypothesis is TRUE.
And NOT that the p-value (from the test data) indicates the likeliness of the null hypothesis BEING true.

Jay Kosta
Endwell NY USA

We all agree with this although I think you should substitute IF for WHEN.

No. There is no THINK about it. It is ONLY applicable WHEN the null hypothesis is true.

??? How does anyone know when the null hypothesis is true? Isn't that the reason for doing these studies and then running these statistical tests?

 

[King Boonen]

Re: Re:

...
This is true Jay, notice it only refers to the result under a certain condition, it does not refer to the likelihood of a hypothesis being true or false,
...
He was attempting to use the p-value to assign a probability that the hypothesis is true. This is categorically wrong. This statistic cannot attach probabilities to hypotheses. This is clearly stated in the article:

--------------------------------------------------
I agree, it's a complex and subtle difference (well to me anyhow...) that the
p-value indicates the likelihood of the TEST DATA being obtained WHEN the null hypothesis is TRUE.
And NOT that the p-value (from the test data) indicates the likeliness of the null hypothesis BEING true.

Jay Kosta
Endwell NY USA

We all agree with this although I think you should substitute IF for WHEN.

No. There is no THINK about it. It is ONLY applicable WHEN the null hypothesis is true. More incorrect rubbish.

??? How does anyone know when the null hypothesis is true? Isn't that the reason for doing these studies and then running these statistical tests?

No one knows Frank, BECAUSE THE P-VALUE IS NOT A PROBABILITY THAT IT IS TRUE OR FALSE.

The statistic knows nothing about the hypothesis, it will give the same value for the same numbers no matter what the data is. You are conflating the statistical maths behind the p-value and its' application to a real world example. You can argue against using the p-value, you can complain it's a poor statistic and you can say it is much too easy to mis-intepret data because of it. But if you want to do this you'll need to suggest a better method and detail why.

What you cannot do is wilfully mislead people as to what the p-value actually is.

 

[FrankDay]

Re: Re:

I didn't say you mentioned the null hypothesis but you don't have to as you are attempting to assign a percentage to the chance of differences being real based on a p-value.
You keep making this false statement that I have bolded, it does nothing of the kind and this has been pointed out to you over and over. Yet more trolling.

Frank is a lost cause when it comes to discussion free of logical fallacies.

Indeed I play a game of logical fallacy bingo when Frank posts. It can be quite entertaining.

My posts aren't really to educate Frank. I fully believe he is being wilfully deceitful as he keeps referencing a link that proves him wrong. They are for the benefit of people who might get taken in by the rubbish he is talking.

In fact, your posts are, seemingly, not to educate anyone. If I post something that is wrong don't you think it would be more useful "for the benefit of people who might get taken in by the rubbish he is talking" to post what is correct than to simply say I am wrong?

 

[FrankDay]

Re: Re:

...
This is true Jay, notice it only refers to the result under a certain condition, it does not refer to the likelihood of a hypothesis being true or false,
...
He was attempting to use the p-value to assign a probability that the hypothesis is true. This is categorically wrong. This statistic cannot attach probabilities to hypotheses. This is clearly stated in the article:

--------------------------------------------------
I agree, it's a complex and subtle difference (well to me anyhow...) that the
p-value indicates the likelihood of the TEST DATA being obtained WHEN the null hypothesis is TRUE.
And NOT that the p-value (from the test data) indicates the likeliness of the null hypothesis BEING true.

Jay Kosta
Endwell NY USA

It's complex, subtle and very straight forward at the same time which is usually the problem. It's the most mis-used statistic in science too probably because it is so easy to calculate and claim it says what you want it to say. It's fine for people to say they don't get it, it's not fine for people to abuse it and think they can get away with it.

So, earlier I posted a link to a study that compared a PowerCranks group to a control group in which they found a difference in power improvement during the study with a p=.125 and a difference in efficiency improvement with a p=0.25. Why don't you tell us all how this should be properly interpreted since you seem to be the only one claiming to truly know but are not telling anyone.